GM 3400 Overheating Issues Explained and Common Problems Misfire Intake Head Gasket

How to fix common GM 3400 issues such as, overheating, head gasket repair, intake manifold gasket repair, no 4th gear and misfires.
Leave a comment with any questions!

[@AB-vm3bn]

You are a sanity saver! I got my '04 Aztek last August as a gift & since February I've had a plethora of issues that I've had to fix. Mostly normal, high-mileage, old-car issues except for the few remaining weird, pull-your-hair-out issues that have had me quite batty. Thanx to this video, as well as comments and replies, I now know what to do. And for the first time in awhile, I am eager and ecstatic to be spending the next couple days in the garage. Thank you so very much for sharing!

[@MrCerebro11]

Thank you for taking the time to make this video, by 2003 aztek overheated and left me stranded, Now that I have it back in my garage and after watching your video I am confident its the head gasket. I will be watching your other videos and tackling it myself, Thank you again for being the type of person who helps put knowledge like this out there for people like me.

[@timmyers7182]

You basicly named like 3 issues im currently dealing with. And thanks to you i have a better understanding how i can fix them. Ty

[@kjvids268]

Thank you so much for this through break down. I wish I saw this video a long time ago. Would have saved me so much money, time, and heartache

[@Reaper1947]

That is one of the best videos I've seen , lots of good info . Thanks for sharing it . TheReaper!

[@lincolnbrown4031]

Excellent help Video. It solved my Headache I haave had for A few years. Thanks.

[@billkc2tux211]

Excellent Video! More information than I expected. Thank you,

[@35RSkyline]

the 3.1l didn't so much have head gasket issues but it dose have intake gasket issues. I hade to replace the lower intake gasket on my 91 Pontiac 6000. he'll of a motor though. ran the shit out if it everyday and when I traded it in it had 315,000 miles on it and it still ran like a top

[@nottoday2238]

Thank you. This video was very helpful. I'm going to try your method on riding the over heating problem. Hopefully it clears the probpem. Again Thank you

[@stevensapyak7971]

5.17.14. The Dexcool coolant will degrade the L.I.M. Gaskets, along with the head gaskets if the coolant is not completely drained from the system. The engine block has drain plugs for both cylinder banks. The back bank drain plug is located between cylinders 3 & 5, & is difficult to access. People go way too long on the coolant service of the system. 2yr/30k miles is what I go. Also the EGR passage port in the upper intake manifold clogs up with carbon, causing a poor or stalling idle. I pulled my engines L.I.M. Off at 82k miles and the L.I.M. Gaskets were just showing slight signs of degrading, not leaking yet. I decided to pull the heads off to inspect the head gaskets. I found that the Dexcool was degrading the head gasket where the opening for the coolant in the block met the opening in the head! It was not leaking yet, but would have in time! I use Fel-Pro metal framed L.I.M. Gaskets & SD head gaskets. Another source of oil leaking is the oil pump drive O-ring located near the flywheel end of the block.

[@TreadMotorsports]

Steven Sapyak this guy hit it dead on!

[@royxdavis5056]

What kinda coolant you use I use 50/50 universal antifreeze

[@kd7cwg]

I got lucky. Previous owner changed intake gaskets and did green coolant. Still going (knock on wood)

[@johnanderson5500]

Yep you hit it right on the head! The previous owner of my 04 grand am 3.4 had changed over from the orange dexcool to the green and saved all the gaskets that way! I got lucky, unfortunately the transmission has issues after it warms up from freeway speeds. When i come to a stop it shifts hard into the next gear all the way to fourth, so i feather it as well as power shift to shift it sooner so it lands a softer shift.

[@kd7cwg]

@@johnanderson5500 if you can, hook up a scantool and monior data, see if the mass air readings and everything is correct. Shift strategy ,etc use a lot of Inputs

[@chadmaytrix]

I have a 1999 Silhouette with 300,000 on the vehicle, replaced trans and engine around 150,000. I intend to drive it until I replace it with a flying saucer :) . I made a modification to the coils and wiring to make it easier to access. I straightened the L-shaped aluminum mount upon which the coils and ignition module rest, then mounted them on top of the intake manifold. It still clears the hood, but makes it much easier to get all those parts in case the coils or module fail. I came about this because a had a no start, that seemed as if it was an ignition module, but turned out it was a broken wire from the crankshaft position sensor. I am prepared to fix this on the roadside, so I try to keep spares with me for things that often break.

[@christophermartin3263]

Thank you so much, I will do that today. Also I was told to loosen header exhaust bolts that converters was bad for going bad on those, I did check the exhaust and could not hardly feel much exhaust. So I'm guessing I will be trying both today. I will let you know how it turns out, thank you agian car friend.

[@Vacationtime247]

I've cut out a section just behind the cat converter and then used a hammer and pry bar to bust up the material inside. Then blow it out by starting the car a few times. If after cleaning out the cat, the secondary O2 sensor reads low or wrong voltage, add in a spark plug non fouler to the end of the secondary O2 sensor. Drill out the inside of the non fouler so the O2 sensor screws on inside. Will keep the code from setting. VT247

[@Daveyboy919]

My 3400 ran hot for 2 years. I changed the thermostat now its perfect

[@grace2u776]

thanks for all the information...greatly appreciated...keep em coming......you the man...

[@somanynamesilltrythis0180]

Very informative, thank you for taking the time to make this video. I have a question about my 2000 3.4l Impala. I'm having a problem with the bank 1 sensor 1 o2 sensor. The scan tool I'm using shows a negative reading during live data. I have another Impala (2003) 3.8l and it says the same thing on sensor 1 bank 1. I was just wondering if it's a common issue or if I'm doing something wrong. I've replaced the sensors, I've used cheap o2 sensors and I've used expensive ones but it still doesn't help.

[@gregmed9002]

I wish I saw this before I changed my thermostat and water pump. Thank u

[@topherd1011]

Seeing that it has an iron block(if I'm not mistaken).. As long as you change fluids religiously and take good care of the top portion of the engine(all aluminum) it has the capacity to go 300,000 miles or more..

[@davidjames666]

you are also knowledgable on these engines. i did my head gasket job back in 2010 70k and an in car partial rebuild of my 160k trans. (clutch pack, sun gear, 4th gear, chain, bands) needed for a failed sun gear and work clutch packs) when i used to put my car in gear, there would be a slap - turns out there also was no hardened chain in the trans, and it stretched, and caused that annoying slap. anywho, something worth mentioning is that GM recommends to keep the surge tanks filled up to full hot when the car is cold. this is extra insurance against the surge hose sucking in air on a slow coolant leak and causing hot spots that can damage the head gaskets. i had my 3400 in my Chevy Venture van since new in 2002 and only have ~185,000 as of May 29, 2020

[@DERRELL_LB562]

I ran a direct wire and removed my thermostat put some blue devil and it's been running good for 2 years with no engine problems 2000 chevy malibu Ls 3100v6

[@brian7316]

helo… what do you mean by direct wire .. I have a 2001 3.4 L Impala and troubles with overheating ..can you help me with that ?

[@brian7316]

@@cathybowen.Shelly ty Cathy.. hope that will fix it...

[@Spidasmokefiya]

@@cathybowen.Shelly was your temp gauge reading normally before replacing the sensor? Or was it always reading all the way cold or hot? Jw, I think I'm having the same issue with my van...

[@otm646]

@@cathybowen.Shelly is that the sensor right at the thermostat neck?

[@jeremiahwilson1781]

Yep. Me too. To hell with Chevy Venture and the 3400 v6 engine. Everything said here was spot on. Be prepared for over heat problems and head gasket jobs. Iam junking mine. Just blew gaskets for the 2nd time in 2 years. Stalled on me about 5o ft from my house at a busy intersection. Had hazards on. Still got side swiped. Tore the whole passenger side to hell.

[@raynumoneray6067]

Thank you for the information. I have a question on my 2004 impala 3.4 engine. Besides the loss of antifreeze I recently noticed a large loss of oil that I had to add, when this engine previously had no oil usage problems. Can a bad intake gasket cause this? I do suspect a bad head gasket though.

[@melvingonzalez4862]

Thank you for sharing ....My friend just baught one i can hear loud ticking. As a friend ill share the info......A viewer from MEXICO......

[@TheSnowsurfer7]

My 2000 Grand Am SE is ticking also the code reader read misfire

[@marissarobinson4388]

Thank you so much i have an 2003 alero & im dealing with this same problem again it ran hot but instead of getting a regular 3400 motor head i got an super charge. & it started over heating & misfiring so when i pour water into it its comes out the motor head.

[@Vacationtime247]

Wonder if one or more of the head bolts got stripped out. But the head has to mate with the block right or else it will certainly spew water all over. The GM 3400's had problem with their gaskets. Best to rebuild the entire thing with new gaskets if your doing one. Because eventually, the head, timing cover and intake gasket will all eventually leak. VT247

[@quenterious1ify]

Thank you, this has helped me a lot.

[@hemetelectricalservices]

Wow I have been messing with my 97 Venture on and off forever! When it runs...IT RUNS!....I learned SO much from this one video about my Mertha...Do you recommend any sources that are HARD CORE Venture specific? New tuck is toooo expensive right now!

[@servant2myking]

Thank you for your videos. They are so helpful! I was wondering if you could identify something for me. I found a small metal tube sticking out of the back of the intake plenum on passenger side. It's right in front of the alternator on my 2002 Venture. It seemed to just have rubber cap over it which had a hole torn in it so I replaced it with another rubber cap. I was wondering if you knew what this tube is and what purpose it serves.

[@Vacationtime247]

+servant2myking It's a vacuum port. Some models may have used them and others not. Replacing the rubber cap was the right thing to do. VT247

[@bigboy-ky3mx]

04 rendezvous overheats, blowing cold air in the cabin and smell a lil burnt sometimes from the engine.

[@jojohn2542]

I've got a heap of a 1997 oldsmobile HELL-OH-ET with the 3400 engine and it is leaking coolant from the passenger side of the engine . I think it is coming out somewhere by the water pump or tensioner pulley assembly but i can't see for sure . I do know it's not coming from the radiator or the hoses. It's almost seeming to be accumulating on the face of the water pump pulley and getting spattered on to the radiator and the control arm etc , but it seems like it's barely accumulating when I'm parked and the engine is idling. I believe driving is when it leaks the worst due to there being alot of coolant in the areas i specified when i popped the hood to inspect the sweet coolant smell i smelt when we were driving it home . There is no coolant in the oil and no bubbles in the reservoir and the heater works great , i just replaced the temp. Control sensor and bled the system properly . If you have any suggestions my email is [e-mail] and i would appreciate any suggestions at all . Thank you , sincerely ,Rod

[@nickmooreakajordanmoore9030]

Dorman heater pipe- would you happen to know what that is? I have a 2000 pontiac grand am gt (black lol) it wouldnt let me leave a pic in the comments but i was wondering if it needed an O ring or somthin cuz i just push it in but it doesnt stay good enough then it starts leaking coolent. It looks like you just push it in but idk if i was missing a ring or somthin cuz it still will start to leak coolent. Very appreciated if you can help

[@rahimd.1870]

Thanks for the great video.. at 2:05, when you're pointing out the intake temperature air sensor, there is a small 90 degree hose that also goes into the intake and is followed into a hole in the engine around back. it's fairly short, about 12 - 14 inches. Do you know what it's called and what it's for? I broke mine while removing the intake in the middle of winter and it was fairly brittle. I spliced it back together with a flexible clear braided PVC hose until I can find a part number. I'm hoping it's not damaging because it's also PVC. but I'm not driving the vehicle at the moment until I'm sure. Thanks for your help.

[@Vacationtime247]

+Rahim D. That tube is for crankcase fumes to be recirculated back through the engine. Not sure if it's got an exact name. PCV crossover tube. As long as it has a good seal and doesn't have any vacuum leaks it's good. Might have to get a replacement from a junkyard. VT247

[@rahimd.1870]

Ahh that makes sense... Thank so much

[@larrymcfarland6112]

right on thanks guys! no wonder it wouldn't take more than like a quart of water after it vented at least a gallon into the overflow. it has been sitting since my last post and for the record Vacationtime knows his stuff. Nobody wants to accept that their car has blown a gasket but that ended up being the case with this montana as well. Another one bites the dust! may as well count on any of these v6's to blow at some point and if you get 200kmi+ out of one, consider yourself good a PM tech. anybody interested in picking up this blown out soccer mom/ G ride for a steal of a deal in UT let me know

[@redhead6351]

i have the 3400 when its idleing in drive it gets hot and than goes back to the cold side but it dont over heat it actually runs goood and another thing the code p0401 keeps poping up i changed the egr valve and it stilll pops up thanks alot besafe always have a great beautyful day

[@Vacationtime247]

Do a coolant system pressure test to check for any leaks in the system. Could just need the air bled out and coolant topped off. The EGR 0401 code is likely carbon build up in the passages. Take off the throttle body and EGR. Run a hard wire down the port and clean it up, suck out the carbon that comes down through the intake. VT247

[@redhead6351]

it does leak a little coolant but im not sure if thats it and egr valve im trying to do that im to sure how but ill try thanks

[@wesleywideman7185]

Thank you for all the info. I have a 2003 olds alero with the 3400 and it has been overheating but it also has been throttleing on it own. I will be going 45 let off the gas and it stays at 45. So my wonderful mechanic first had me buy a water pump then the temp sensor and he was sending me to get a thermostat when i noticed that neither of tye fans where running and it was well above temp at this point. So i check fuses and cleaned relays but fans still dont work. What do u think. And i checked the oil cap and dip stick and do not see any white residue nor can i spot a leak when u showed to look. I truly appreciate your help.

[@Vacationtime247]

Bleed the system of air. If it runs fine for a while then overheats along with again having air in the system, it's probably a bad head gasket. Might try a system pressure test to confirm. As far as the staying at the same speed, check for vacuum leaks and if the throttle body is closing all the way. To test if the fans work, unplug the temp sensor and they should come on, but this will trigger a code. Yet, it's a quick easy way to tell if the fans are working. VT247

[@wesleywideman7185]

Vacationtime247 WOW man I didnt really think you would respond. I wasnt sure like how old your stuff was. I really appreciate it. I think my biggest problem in the situation was the guy who I thought was a mechanic but it turns out he is good and putting on new parts which if i had a garage full of tools and KZbin i could probably do. So today an old newer friend of mine called me and i totally forgot he us a certified mechanic and works at a shop. So he looked it over today and tomorrow he is going to take it and fix all this crap. I will pass on your info. He did say that i definitely have to buy a tensioner pulley because he could actually see it moving around and its possible that was causeing the throttle issue. And once again I really appreciate it it's good to know that I can reach out to someone if i have anymore issues.

[@jimmyjohn7929]

Here's one for you: 2000 Silhouette 3.4 was overheating. Replaced t-stat because it was sticking. Purged air using a hose tee on the heater hoses and raising it above the rest of the system. Purge, fill, repeat until there was no air left to purge. Both fans operating. No white or otherwise unusual exhaust smoke. Engine ran great, heater was hot, temp gauge fluctuated but stayed generally in the middle. Took it on the highway for about 5 miles at 50-55 mph and began to hit the red zone. Tried using 3rd gear to accelerate coolant flow but that didn't seem to have an effect. Engine started to lose power as I pulled off highway. Slowly opened hose tee to see if there was air in there again, and there was a lot. Released steam slowly for about 5 minutes, then started it back up and drove it home. Had to release steam two more times to make it home. Possible diagnoses: 1.) Head gasket dumping exhaust into the coolant and pressurizing it, but if that were true wouldn't there be white exhaust smoke? 2.) Water pump not moving coolant fast enough and it's boiling. 3.) Radiator plugged with rust and Dex-Kill goo. 4.) I didn't really get all the air out.

[@Vacationtime247]

Pretty sure it's a blown head gasket. These engines are known for gasket failures. Might try a coolant system pressure test and see if it holds pressure. Could try a chemical test and check for exhaust gases in the coolant. It's a blue dye that changes color in the presence of exhaust gases. If you do have to fix the head gaskets, do the entire engine, timing cover, head and intake. They all go out eventually on these motors. VT247

[@jimmyjohn7929]

@@Vacationtime247 Forgot to say I did go to AutoZone and rent a pressure test kit. It held 16 psi as long as I could hold on the GM cap that didn't fit perfectly. A full 60 seconds maybe; didn't get a chance to fix the cap issue. I was also thinking of the chemical test. If it's a head gasket, I don't have the time or space, and we'll just hock the van on craigslist and try and get $400 for it.

[@dlocstaa.j5363]

hey my kar blows water out my intake after its on for a while what u think it kan be?

[@davestran]

I have a 2000 Impala w/ 3.4 and it seems work as far as morning startup and running the heater, however when you look at the temp gauge it will be 165 or so and only one time I put coolant in was when we found a cut or bad area to the overflow eank at the radiator, we cut off the bad area and replaced no more leak. But yesterday I had to make a road trip of about 60 miles oneway going down know problem 59 outside temp, coming back 72 outside, about 175 on temp gauge and when we got 12 miles from home the message center flashed LOW COOLANT LEVEL, I pulled off the road and checked coolant tank and it was 4 or 5 in down from top, both hoses had pressure and never got to midrange temp untill I got home. I checked levels the next day and everything was fine. Now the Service Engine light in the message center is always on, been reset I dont know how many times, got it on a big computer and the only thing he could find was a BCM maybe bad or what have you, but the system itself is fine. Would the BCM cause something like I mentioned ??? The car sit for 2 years, because the lady bought a new car (traveling nurse) The gas cap doesnt stay tight, the radiator cap (looks) like it could be replaced (but not leaking that I know of) As far as water pump or thermostat I dont have a clue. Im disabled and I needed a car and was given this one, but I cant afford any big repairs. Can you PLEASE HELP ME ??? Thanks

[@Vacationtime247]

There may be a coolant level sensor on the car, may be faulty. Also try adding fluid all the way up and then bleed the air out of the system when the car is at operating temp. There should be two bleeders. One on top of the water pump, the other on top of the water neck outlet by the thermostat. VT247

[@ednja]

On my Venture, the coolant level sensor is on the end of the radiator below the radiator cap. If the coolant level is 4 or 5 inches down, then the coolant level sensor should be signalling low level, which in your case it did. I recommend using a spill-free funnel for bleeding the air out of the cooling system. That's what I use and it works great. You should do a coolant pressure test though to check for leaks. You should also check to make sure the head gasket isn't blown. Use a combustion leak tester to determine if there's exhaust in your cooling system. Also make sure there's no oil mixed with your coolant or coolant mixed with your oil. When you fill up your radiator, also fill up the coolant reservoir to the hot level line. GM recommends filling it to the hot level line while the engine is cold to ensure no air gets drawn into the system.

[@tarab4617]

I know this video is years old, but maybe someone can help. 2000 silhouette. The low coolant light goes on and off but there's plenty in the reservoir and radiator. It wants to overheat when idle. No bubbles in the coolant reservoir. No white or milky junk in the oil or the cap. No white exhaust. This lead me to think the gaskets are fine. I'm thinking the thermostat stick closed or coolant temperature gauge might need to be replaced, or maybe there is a clog in the coolant system somewhere? Now I'm wondering if I missed something or there could be a different issue because you state that the thermostat going out isn't all that common. Is there anything else I should be looking for?

[@StillinsStyles]

Thank you.

[@joshfifer]

I just purchased a 02 rendezvous and the only motors that is suppose to come in it is the 3400 but the intake cover says 3100 how can you tell the difference and are they interchangeable with transmission and everything

[@KristenNMartinez09]

Whats is the normal operating range on the temperature gauge. I am usually at the 11 oclock and 12 oclock in city driving. But around 1 on highway driving. Thank you for any information

[@metalprovo]

I don't know why I can't see my previous message. Anyway, what is the cable that you touch with your finger for in the min. 5:27? in my 2002 venture the right side cable is loose and I can't see the other part, which has a white plastic part. thanks

[@draeallen]

thank u for responding so far I've taken it to several shops no one knows so been trying to research why I would have heat, air, holds pressure,no visible leaks, no coolant lost, no milky oil on dip stick did notice little condensation under the oil cap but that's normal right? no unusual colored smoke or consistency coming from tailpipe, fans working no pully loose, belt look fine however at start up does have fume like smell by the way it's a 3.6liter

[@Vacationtime247]

+drae allen It's possible that the thermostat needs changed out. If it's stuck open it would cause overcooling in most situations. My first guess is that a gasket might be leaking internally because the gaskets on these engines from the factory weren't good. VT247

[@kd7cwg]

I push coolant into the radiator with the coolant exchanger (under light pressure) till coolant comes out of both bleeders. Found it the fastest way to get air out. I am at the point I have to do the gaskets though

[@Vacationtime247]

Do all the gaskets while you're in there. Like the timing chain gasket as well. VT247

[@davidhougham7442]

Thanks for the help mine just overheated today is there an easy way for me to test the thermostat to make sure it's not stuck?

[@Vacationtime247]

If after running for a while, one radiator hose is very hot and the car overheats but the other hose is cool, the thermostat is probably stuck provided it has sufficient coolant. These engines tend to have issues with the blown gaskets, intake, head and timing cover. A coolant pressure test would be helpful too to find any leaks and see if it holds pressure. VT247

[@cardozita2cool]

I tell you man those engines are a piece of work ,I drive a 03 Chevy venture sometimes drive me crazy

[@Vacationtime247]

No doubt. If you get a vehicle with one of these engines, plan on replacing all the gaskets. VT247

[@ryans413]

Vacationtime247 Got a 3.4 V6 in my Grand Am no issues has 140,000 you guys most not know how to look after your motors

[@jonathanguyer2754]

I have a 2000 chevy venture van 3.4L and the idle has been getting steadily rougher for the past couple of months. I changed the sparks recently to fix a separate issue but I still have a dead spot when I first start the engine that lasts only 1 second before the engine kicks in again and idles. Anytime I am idling the engine is running rough and the temperature increases to 1/2 way and up to 3/4 now as well. Temp will decrease at normal speed limits. After watching your video and another one that specifically focused on my make and model, I am leaning towards thinking that this could be either an exhaust vacuum leak, a misfire or an intake manifold gasket issue. What would you recommend I do now? Thanks for your time!

[@michaelstjohn6086]

what was it?

[@melvinharrison8924]

I have an 03 silhouette. Last year i did a head gasket replacment due to engine over heating. Our one means of transportation. Ran top notch till it all of a sudden threw a po303 code. Cylinder three multiple Misfire. Spark pkug and wires and coils all check out ok. Issue is when you try to accelerate it tries to bog down. Check engine light startd to flash. Once gas pedal is released engine light eventually goes back to solid on. Checked ohm reading on the fuel injectors and got 11.6 on #3 and #1. Still main mode if transportation so any and all feedback is welcome. Thanks

[@Vacationtime247]

Here's what I'd check if it were mine. Getting to the injectors can be difficult. Check each injector with a noid light, make sure it's getting power. While it's dark outside, mist water around all the area's of the #3 cylinder and make double sure it's not the spark system. Had coils that look good but are cracked and will throw blue sparks if there is a mist of water around it, causing it to misfire. Might swap the coil pack and wire to another cylinder and see if the misfire moves. Could try tapping on the #3 injector to see if the idle changes. Just a few suggestions. VT247

[@melvinharrison8924]

Vacationtime247 thanks. I tried swapping coils and it still had same code. Its hard to grt to the injectors like you said so how would you suggest reaching them with plenum on?

[@melvinharrison8924]

at idle there really is not much of a mis that is noticeable. But I will try the water trick to see if spark is jumping out of #3 coil area. Stay tuned...

[@deecharley]

Hi, I had a new water pump and radiator flush. My vehicle was running fine now it's overheating. The radiator and spark plugs been replace. Help plz

[@mfernando8639]

Hello. Thanks for your video. I recent ran my 3400 with low coolant and the engine overheated badly. I am now getting a P0303 code and the vehicle is idling very roughly and I cannot exceed 50km/h without the engine light flashing. I'm concerned I may have cracked the cyclinder ...any idea how I can go about troubleshooting? Thanks!

[@Vacationtime247]

Probably a blown head gasket. Could try a coolant pressure test, see if you hear air / water in the cylinder. Do a compression test perhaps too. Only way to tell if the cylinder is cracked is to tear it down and check. Bit of advice though, if your doing one gasket, do them all. Intake, head and timing cover. Teflon tape the oil sensor while your there too, they sometimes leak. VT247

[@howardhagadorn9443]

I inheirited my mother's 03 rendezvos with the 3400 engine. It's never had anything done to it engine wise, just a ton of front brakes and wheel bearings. When I was bringing it home, the temp gauge flew up to hot and the bell went off and before I could pull over it dropped back down into the normal zone. coolant was low in the radiator about a quart and the overflow was down to where the hose wasn't in the fluid. I don't have any sign of coolant in the oil or any sign that I can find of coolant leak. I've seen a lot of videos on burping the cooling system. I'm hesitant to start tearing it apart without learning more. I also have no heat in the cabin, but tho the engine is at normal operating temp. The blower works on 1,2,4, and 5 and I've seen several people on here saying that heater controls have bad connections resulting in burned off contacts and there is a funny smell, kinda like something is burning. Got any advice for me? Or do you wanna buy a rendezvous cheap? lol

[@Vacationtime247]

Fill the radiator and reservoir up with fluid with engine cool. Start the motor and bring to operating temp. Turn out the 7mm bolt on top of the coolant neck or on top of the water pump (that black metal pipe). Let the air bleed out and tighten the screw. That should let the heater blow warm air. VT247

[@bwill578]

Mine has had the intake manifold and head gaskets redone. Not smoking and no coolant in oil. Also it's not running hot but I am losing coolant. I can fill up the radiator and start it up and drive it for 15-20 minutes and my low coolant light will come on. I've also changed that sensor as well. Heat works pretty constant. I also have virtually no pressure in the system as I can drive the car like I said and remove radiator cap no problem. Thoughts?

[@Vacationtime247]

Do a coolant system pressure test. They rent the tool at Autozone. Basically you hook it up and pump up the connector. It applies pressure to the system. Make sure the pressure doesn't drop rapidly. If it does, check for leaks or sounds. VT247

[@edwinwilhelm7999]

Why are the coolant fans not running on my 2000 Olds Sillouette Van 3.4 L ? Fuse 1 is good.

[@wesleywideman7185]

Ok so I am having trouble finding the bleed plug for coolant on the drivers side. All the videos i have watched show a plug on the passenger and driver side but those werent aleros same engine though. Is there really a second bleed plug on the driver side of the engine ? And just to clarify. The 2 cooling fans , do they both come on at the same time with 2 speeds or no. Because im going out to junk yard to get new fans. My mechanic couod actually feel that the motor wasnt moving right.

[@Vacationtime247]

Believe my fans are either on or off not variable speeds and come on at the same time together. Could check yours by unplugging the temp sensor. It would set a code off, but would turn the fans on. The code would reset after a few starts. The bleeder screws are pointed out at 2:45 If you're having to continuously bleed air out of the system there's a problem. Doing a coolant system pressure test is a good way to find any leaks. VT247

[@williambrucesanders6878]

2000 olds sillette replaced cracked heater hose in the back of the engine. Now over heats. Do I need to bleed the system? Thermostat? Help please

[@kristianbonis483]

I was changing the coolant temperature sensor in my 2001 malibu and the part that it screws into cracked around the sensor was wondering what the part name is it screws into

[@scotttwombly6528]

Bought a Impala new in 2000. Highly maintained it. 130,000. Both heads cracked. New loaded GM heads were a good deal. Lucky the colant leaked into the combustion chamber.no Water in the oil. Took me 3 days to install both heads. Getting slower at 58 years old.

[@Vacationtime247]

No kidding. Not getting any younger myself. Used to be able to work all night on a car then wake up and do it all over again. Now, the ol' back makes me pay for any work done the day before. lol VT247

[@RonaldDCass]

58 is getting old! 🤔🙄🤭 I turned 80 last week. I bought an 06 Buick Terraza with 3.5 cheap because it started to overheat. I tried everything short of gaskets. Nothing worked. No cream on rad cap or dipstick, or oil on surface of coolant. There's combustion gas in cooling system, so I am now half way to complete. Got FelPro gasket set. In Missouri it's a bit warm to work on cars outside. My heads are not cracked or warped, so almost ready to put everything back together. I don't think I'll be able to do this many more years. Most of 3 days so far. Hope to drive it within a week.

[@dannyle5440]

Hi I have 2003 Chevy venture don’t know what going on but when I drive I have good heat and the temperature normal but when I park or wait for the red light the temperature gate go up hot and no heat. I put new radiator new water pump new cooling sensor new thermostat and still does the same thing I wonder it have to do with the head gasket please let me know thank you

[@66luby]

Do you know much about traction active light and issues with front end, I put 2 new hub assemblies and new breaks , but when i turn sharp or stop while turning the wheel i hear grinding and when i start the car most often the traction active lights are on, they go on and off through a ride around town. Thanks any advice.

[@Vacationtime247]

+barry luby Sounds like something is rubbing or hitting. My Aztek does the same sometimes with the light coming on. No big deal, just make sure the connection from the hub to the connection wire plug is together good or just wire it straight through with no plug in. VT247

[@candicehuston1747]

I mixed the push rods up in the 3.1 v6 motor, the head closest the radiator from drive side to passenger side, what order do they go in?

[@Vacationtime247]

Intake pushrods are shorter than the exhaust. You'll know which is which by looking at where the valve goes. If the valve can be seen with the intake manifold off, it's the intake. If you can't see the valve, it's for the exhaust. VT247

[@wallen465]

So I have a 2002 aztek, replaced head and intake and valve cover gaskets, new plugs and wires and coil packs, and fuel pressure tested at 44 , so just wanting to verify that the pump is bad car doesn't start, , before I spend the money in getting one an

[@richardcallahan8698]

Temp is right in the middle. 4t65e seems to desire a few degrees less temp; Ive got mercon atf. ( The normal 2005 atuff) My 4t65e hard shifts (thumps) at temp. So, Q: Any guess? Maybe it is an ATF viscosity at temp? How can I get a few degrees less temp? Maybe some ATF thickener like STP. I am thinking of using 160 stat and hard wiring radiator fan to 100%. Id really like to stop the trans to stop slaming shifts. Kinda think that holding temp at 160 will fix it. I do appreciate your thoughts! Old Timer Richard.

[@Vacationtime247]

Check for vacuum leaks. Had this problem in the past with bad shifts and a leaking vacuum hose. Might check the mass air flow sensor too. VT247

[@richardcallahan8698]

@@Vacationtime247 I suspect I had an air lock in cooling system. The 4t65e needs the correct temp. to function well due to its advancing age. Getting the air out w the bleed screws looks like all it needed. If troubles are marginal, I will add an aft market trans cooler. I do think my valve body needs care due to wear and blow by. Theory is the cooler will keep the viscosity up by preventing excess thinning of atf fluid. Thanks for your knowledge.

[@cuteblanca5272]

What is that hose you pointed to saying it can cause a vacuum leak

[@Vacationtime247]

Not sure what the name of it is. There’s a rubber grommet that the vacuum tubing goes into that fastens to the upper intake. Make sure it is fully seated and secure. Might have to remove the metal throttle cable bracket to see or fix though. VT247

[@stevenmartinez8208]

Have an 2003 Impala 3.4 liter over heating issue ofcourse changed out da thermostat but didnt resolve da problemTried bleeding out da cooling system cause on a youtube video one of da links said da system was pressurized..but as yu xplained in yur video on da 3400 engine there are 2bleeder valve one on gooseneck housing but da other as states on video never should be touched cause it will make yu have an all day headache..lol..but wat if yu never really can get water to come out of da bleedere valves..problem i am having now..so frustrated wit da Impala please help any suggestions are welcomed..thanks

[@Vacationtime247]

Fill up the radiator and do a coolant pressure test. Could have a leak or a blown gasket. Leaks will be easy to see after being pressurized as water will come out in force. If it doesn't hold pressure and no leak is found the head gasket is probably blown. VT247

[@sugarsweet71]

Hi need help.My A/C stared to blowing warm and not long after it was blowing warm air in the suv.Not to long after motor started to shaking .I check they oil it same clear.But the next day I start the suv buick rendez nous and it misfire and white smoke come out.It a 2005 buick rendez nous.Please help me

[@YAHOVAHSEESPEACE]

2004 Pontiac Aztek 3.4. Temp gauge fluctuates while driving and stopped at light. Dipstick and oil fill cap look clean(not milky)

[@Vacationtime247]

Probably a bad head gasket. Do a pressure test of the coolant system. VT247

[@robinsonorughe536]

H

[@joseayala8497]

i have a 2005 buick rendezvous 3.4 it seems to over heat after about 30 to 45 min. ive changed the temp. sensor thermostats. an the fans not to sure if my fans kick in properly when i turn ac on they seem to kick in with more speed oil is good no smoke comes out from the exhaust

[@Vacationtime247]

Do a coolant pressure test to check for leaks and holds @12-15 psi VT247

[@jakebraun9047]

My 2005 3.4 buick rendezvous has a high idle problem do you know what I should look for? I already replaced the idle control valve and the coolent temp sensor.

[@Vacationtime247]

+jake braun Check for vacuum leaks. Break out an old school vacuum gauge and the readings will help diagnose too. You can check for vacuum leaks with a water bottle. Check for differences in idle when squirting it around. Also check that the throttle plate / butterfly is closing all the way. It can be cleaned with some basic carb cleaner. VT247

[@ttshirtnpanties]

we have an overheating problem on a 2001 impala 3400 ,fan do not come on unless the air is on,temperature gauge gets to halfway and two lines behind halfway ,when the car get hot the tramsission only shift one time causing the motor to idle very high please help

[@danielhammond175]

had a crankshaft pulley go bad replaced it and the car began to shake under a load. Started throwing a knock sensor code replaced knock sensor and pigtail pulled the pulley back off and replaced crankshaft sensor. still shaking throwing knock sensor code. Actually runs better if i unplug the knock sensor but still shakes

[@johnniedelgado484]

good morning Bud. I have an 04 olds silhouette with a 3400 motor and I'm reading 2 codes. 300 & 171 codes. I did an in house oil change and plug/wire change and oil pressure dropped. I have to little flared tip things at opposite corners of the upper intake manifold and they're sulking in air. are these supposed to be capped off or lead into some other intake hose? also, bank 1 code (171) is that an upstream o2 sensor? I changed out the oil pressure sensor already too. my car is riding ROUGH and as soon as I turn on the a/c I lose power. please help.

[@Vacationtime247]

Sorry for the late response. Been in Alaska working as a mobile mechanic. Back on the Cali coast again. Sounds a lot like a vacuum leak. I shoved a piece of sponge in between the bracket and vacuum tube. There should be no vacuum leaks. A misting spray bottle of water can help find vacuum leaks. Spray and monitor for idle change. VT247

[@randylee2549]

@Vacationtime247 I do not have enough heat, 2000 Montana Van, runs not more than 1/4 on the gauge scale, the heat is not HOT, just luke warm. Thoughts? otherwise it runs good

[@Vacationtime247]

Fill up the coolant to the appropriate level. Run the vehicle until warmed up. Bleed out the bleeder screws until all the air is gone. If the problem persists, do a coolant leak down test. This will expose any leaks that may or may not be visible. It should hold pressure and not drop quickly. VT247

[@angelrobles381]

My alero olds mobile 3 .400 iput tomany parts and he stil. Miss fire cilinder 1 but i pull the spark plug out its oil an the spark plug some people said is the head gasket can't you answer my question please

[@karlielovell9331]

I have a 2002 pontiac montana with a 3400,replaced the thermostat and still over heating, and head gaskets are good next option is water pump any suggestions?

[@Vacationtime247]

Do a coolant pressure test. Can do the loan a tool at Autozone. See if it holds pressure. If so, then try the water pump. If not, find the leak and repair as necessary. VT247

[@en392]

03 impala 3.4. It has a fairly new spectra premium radiator from auto zone. I seen a leak for awhile of transmission fluid from the transmission cooler line. The end that goes into the radiator. I just changed the adapter with the horse shoe on it and still a small leak. Should I just claim my warranty thru auto zone or is this a easy fix?

[@Vacationtime247]

+en392 Not had to do that repair yet. Does it need a new O-ring? Might be an easy fix. VT247

[@lassenielsen4340]

thanks for great video - i have had this problem for a while now. rough idle, but ONLY when its warm, and as soon as i push the pedal juuuust a bit it runs fine . i have replaced tps and iac , cleaned throotle body, and replaced several vakum hoses , but it stiiiil has a rough idle . COULD it possible be a simple thing as a fuel filter ? i drove it emty for about 5 months ago , and....did it come after that hmmm . i just think that IF it was some fuel problem it shouldn´t run great, but correct me if i´m wrong , could it be a bad intake ? it has some time that noise in idle like a misfire ...like a bad sparkplug wire, but changed em for 6 month ago with plugs . i´m going crazy cause if it a bad intake it should not drive that god. it JUST a rough idle - what am i missing ? please ...please help me if you got a clue

[@Vacationtime247]

Check fuel pressure, the port to check it is behind the power steering pump on the passenger side near the alternator. Could be a bad fuel pressure regulator, partially clogged fuel filter or a weak pump. Not sure if it's ever had the gaskets replaced, but these engines are horrible about blowing gaskets. If it ever gets hot or to cold, try a coolant pressure test to see if it holds pressure. VT247

[@lassenielsen5492]

@@Vacationtime247 thanks a hole lot for that reply. I will check it later today, as soon as i got that egr valve on again 😡 pain in the but to get to . Noticed that the pipe going from rubber between air filter and throttle body in to the valve cover - dont remember its name BUT it was totally lose in valvecover, MAYBY its that but i dont think it is. Next step is the fuel way. Never ever had a car with so many problems all the time . Especially the fu....ng gearbox ! BUT when it drives im on top off the world. Some cars you just get a feeling for and it aint JUST A CAR you know.

[@travianbernard9880]

i have a p0300 with a p0137 any ideas?

[@patrickwilliams4465]

Ive got the evap issue should i start with the evap solenoid over the gas tank or the part by the throttle body the o2 sensors are reading bad also figured that was because of the evap letting out bad emissions too much unburnt fuel the 3.1 liter 2002 buick century has 85,000 miles on it

[@Vacationtime247]

Check inside the upper intake where the EGR bolts on. They are prone to carbon up real bad there through the passages. Another evap issue I once had was the check engine light would come on due to a bad FTPS (fuel tank pressure sensor. It's located on top of the tank, but can be reached under the vehicle. VT247

[@draeallen]

my upper and lower radiator hose are staying cold does that sound like hard gasket plenum gasket or thermostat had waterpump replaced unless it was faulty

[@Vacationtime247]

+drae allen First bleed the air out of the system at the ports above the thermostat housing and the water pump black tube coming out the top. Then, do a pressure test of the coolant system. If it holds pressure, it's not a gasket. If not, there's a leak somewhere. VT247

[@davekarter3380]

have 2000 impala with 3400. heatercore was bad so i bypassed it .(7-8 mos. ago). recently it has been overheating. water is not circulation too top of motor. took thermostat out. still no circulation. put in new thermostat and no change. builds pressure and pushes water out overflow tube. no sign of blown head gasket but does smoke a litttle when full of water. no water in oil and has good power. could it be waterpump

[@mesheeplaisance1759]

dave karter same problem

[@dimitraleara6386]

I'm currently having an issue with my 2004 Chevy venture it over heats and goes from warn to hot when u get up to a certain speed

[@johnanderson5500]

Check your fans. While it's idling in park, turn on your ac and see if your fans kick on. If they don't you have a problem some where. I had that problem which was the ac relay which actually poped and prevented my car from starting because it blew a fuse that shares the pcm with the ac. I own a 2004 Pontiac Grand Am SE1 3.4L but these Pontiacs are almost the same if it has the same engine. Mind you i say "Almost" the same. Anyway what i did was pull out the relay block in the fuse box, and replace the blown fuse i had, then manually hooked both fans up to a switch to the battery. This means i can turns the fans on anytime, but i don't have ac. Hope this helped. By the way if you're ac doesn't work and you don't care you can eliminate the ac radiator in front of your actual radiator for more air flow to keep it cool. Mine was already empty so i cut it off. But if its full your supposed to have it professionally emptied.

[@petrdrbal10]

HI ,I got 04 3400 grant am - overheting -bubbles air to degas overflow tank - no cup on radiator (confuses me I like more the one like you have), I did the pressure test I got on all 6 plugs about 155 pressure ....so now wander if it is water pump or thermostat ..oil is clean ... any idea ? Thanks for coments in advance.

[@Vacationtime247]

Get a radiator coolant pressure tester from Autozone loan a tool and do a pressure test on the cooling system. Believe the Grand Am pressure cap is on the overflow tank similar to an Alero. Try this also, fill up the cooling system, turn the car on letting it get up to operating temp and then bleed out the bleed screws. The vehicle will run at normal operating temp for a while then overheat after a short time. Bleed out the screws again and there's air in the system. This would indicate a bad head gasket. You stated you have 155 psi x 6 but what about leak down? The compression peak is met but it leaks down shortly after. Exhaust gases most likely getting into the coolant, i.e. the bubbles in the overflow. Personally believe you have a bad head gasket. FYI, if you do replace them do ALL the gaskets while your in there including the timing cover. kzbin.info/www/bejne/gWbQqJ2Ngcqgd5o VT247

[@tbone11381]

I have a variable engine shut off its usually going down the road happens usually after going up a hill but not always I redid the heads a while back I thought it was a fuel issue but changed filter pressure was great. after it shuts off I pull over wait anywhere from 45secs to 5 mins it starts right back up. any ideas?

[@Vacationtime247]

Could be the wires for the fuel pump shutting it off momentarily. When it doesn't start, listen to see if the pump kicks on. VT247

[@darrenkamerling2476]

Hey i have a question about over heating it doesnt over heat completly goes about 3 fourths of the way then goes back down once fans kick on but i believe i have a slow leak where the bleeder is mext to the water pump l.. What type of sealer should i use on that o ring

[@Vacationtime247]

If you're referring to the metal tube that has the bleeder on, it has an o ring. I took mine off, cleaned it and also added some black silicone around it. Didn't leak anymore after. But, might do a coolant pressure test to find any other leaks and see if it holds pressure after. VT247

[@alexstamas3132]

Hey my buddy replaced his thermostat in his overheating 2001 Buick century. Now when he tries to start it up it cranks but won't actually start then possibly a back fire or burp.. what should I look at first to address this? Probably occurred during poor mechanic work

[@Vacationtime247]

Sounds like a wire or plug in didn’t get put back. Look for loose or broken connectors. VT247

[@annettecobb6437]

Vacation time, my 3.4 l8tr 2004 grand am overheats but the gauge doesn't reflect that. I believe the gauge works cause it move between 190-215 degrees. But steam is coming out from under my hood sometimes. What do you think?

[@Vacationtime247]

Get a lot of these type of questions about this engine, so here's where I'd start if it were mine. Do a coolant system pressure test after filling up the overflow with water. Once pressurized, listen and watch for water to come out. Bet that a gasket is blown and it's leaking somewhere. Replaced the head, intake and timing cover gasket on nearly every GM 3400 I've had. VT247

[@Atreus21]

I'm the kind of guy who buys cars before I go to KZbin to find out that there're entire videos dedicated to the stupid problems that these engines have.

[@Lincolnator721]

I have a 3.4 buick rendezvous, hopefully it'll be alright lol

[@scorpio2nyc]

Lincolnator i had the same car it overheating problem made me crazy

[@Lincolnator721]

Rodrigo Batista How many miles did your Rendezvous have? Mine currently has 211k miles and no overheating issue *at least not yet anyway*

[@scorpio2nyc]

Mine had 134.000 i had to get rid of the car for 1100 dollars you are lucky with this milage keeps until it drops.

[@Lincolnator721]

Rodrigo Batista dang, that is really low miles for it to overheat. i'm sorry about that, i'm sure you were upset. and i know i've heard and read a lot about these cars overheating, electrical issues, and rear end noise. luckily i have none of those besides the rear end noise (going over bumps) other than that it seems to ride nice. guess it's the chance you're taking whenever you buy a car whether it's new or used

[@draeallen]

I took it to the shop and they said didn't need thermostat I think they saw the housing and felt it looked fairly new and said I needed a engine instead because there's a lot of highway miles the temperature gauge goes up but I shut the car off b4 it could go to the red zone

[@TheMrmmkkpro]

Working on a 05 grand am 3.4 and I have bled it over and over and still getting air bubbles , if I keep bleeding it it will be out of coolant , thinking head gasket maybe , any suggestions ? Thanks

[@Vacationtime247]

This sounds a lot like a bad head gasket to me. Use a coolant system pressure test gauge (can be rented at Autozone loan a tool) to check for leaks. Hope this helps. VT247

[@kirkmarthia944]

Hello. Basic cost to do the head gaskets and intake manifold gasket job ??? To help with overheating

[@Vacationtime247]

Depends on the shop. It's certainly not an easy job! VT247

[@jaykriesel2477]

Im pissing oil near a sensor above the starter and below the exhaust manifold on my 05 Equanox..have you seen this?

[@Vacationtime247]

Sounds like the Oil Pressure Sensor. Remove and replace. Wrap some teflon tape around it before installing to prevent any seeping. VT247

[@jpr7650]

I drained my radiator to do a radiator flush because I found some sludge under the radiator cap and now it wants to overheat and it didn't before do you think it's because I have air trapped in the system or do you think the thermostat is bad from sludge buildup

[@Vacationtime247]

No. My guess is that the head or intake gasket has blown and it won't hold pressure. Try filling the radiator and bleeding the air from the bleeders. If it stays cool shortly but then eventually overheats and you have to rebleed the system over and over it's the gasket. That or try pressurizing the system with a pressurized vacuum pump hooked to the radiator. Then check for leaks or hissing. If you do the intake, go ahead and do the head gaskets. Trust me. VT247

[@Dopeweed79]

Quick question, the only time the radiator fans come on is when I turn on the a/c, don’t know for sure if they come on once the temperature reaches the 200 mark but it hasn’t went above the 200 mark yet. But is this normal or should the fans kick on and then off??

[@kd7cwg]

My low speed fan turns on at 221 and off at 200. They are programmed to idle at that for emissions bs

[@AuzzAustin]

My fans were just broken I just wired a speaker wire to the sensor and to the fan fuse. They kicked right back on.

[@Vacationtime247]

Glad that worked! Sometimes it’s just something easy. VT247

[@223shawty]

Im getting a P0300 code on my 1999 alero and i cant seem to find why

[@jonathanyates5198]

I have a 2002 Chevrolet impala 3.4L that overheats when going up mountainous roads during summer. Coolant is level, fans work, thermostat works as it should, new coolant pump, and just has coolant system pressure test done but can't figure out the problem. Live in Southwest Virginia

[@Vacationtime247]

Sounds like you've covered all your bases. When you say it overheats, does it puke out the overflow tank? If not, then it may just be getting hot but not necessarily overheating. Only other suggestion would be to make sure there aren't any blockages in front of the radiator. May try pressure washing to clear the venting fins. VT247

[@ericknoblauch9195]

Our mechanic said the aftermarket oem quality water pumps are garbage on these engines. We had the same problem. The intake was leaking and the gaskets were replaced. Then the Gates water pump failed after just one year. The water pump caused overheating again, and it blew a head gasket. The top end was rebuilt, and a GM Goodwrench water pump installed. Since then no problems, and that was five years ago.

[@jlange2011]

My 2002 Oldsmobile Alero has the 3400, My cooling fans do not come on when engine is hot nor when I turn on the A/C. When I unplug the temp sensor the fans with come on immediately and stay on. I still replaced the temp sensor but that did nothing.

[@Vacationtime247]

How high does the temp get? Mine usually has to be over the 3/4 mark for the temp. My advice would be to hook the car up to a good OBDII scanner and see if you can turn on the fans. Might be that it's not getting a reference signal to turn on the relays that control the fans. VT247

[@jeremiahwilson1781]

Joshua Lange 2002 Venture here. That is a common problem as well. The fans i come on really hot or not at all.

[@Spidasmokefiya]

What triggers the reference signal to the fans? Is it the coolant temp sensor or the PCM? Jw

[@alvinspmn6120]

I purchased an 01 Aztek GT in 2002 and really enjoy this vehicle. Over the last twelve years, the intake manifold and head gaskets have been replaced once. I have a problem with the engine temperature gauge showing an increase in coolant temperature when I'm in city driving conditons. At the same time, the automatic transmission starts "hard" shifting. The cooling fans do not run unless the AC is turned "ON". How do I make the cooling fans turn "ON" without running the AC?

[@Vacationtime247]

The coolant fans will only turn on when the temp gauge gets pretty high unless you turn on the A/C. You could get a tuner program and reprogram it that way, otherwise it is factory set. Mine does the same thing. VT247

[@mattthomas4570]

Vacationtime247 Hi, Thanks for the video. I have an 03 Malibu with a 3100 engine. It overheats. I unplugged the coolant sensor temperature and the fans come on. The fans don't come on otherwise. What would you look at next if I know that unplugging the sensor turns the fans on high, fans work and fuse it good? I have not tried to bleed the air out of the cooling system yet because the fans don't come on I figure it is electrical. I have seen suggestions of a secondary fan control however I am not sure how they are wired in or if this is the fix needed. Do you have any feedback on this? www.autozone.com/productComparisons/productComparison.jsp?originalUrl=%2Fcooling-heating-and-climate-control%2Felectric-fan-thermostat%2Fchevrolet%2Fmalibu%2F2003%2F6-cylinders-j-3-1l-sfi-ohv%3F Thank you, Matt

[@alvinspmn6120]

Vacationtime247 Situation- 2001 Aztek runs perfect at highway speed, temp gauge reads normal. Then I slow down for city driving and the temp gauge registers a higher temp (needle moves up "1" mark below the overheat range). At the same time, the computer instructs the transmission to raise line pressure and the transmission begins harsh shifting. I parked the Aztek in the driveway with the motor running and opened the hood. The cooling fans were not running. I measured the coolant temp with an infrared scanner and watched as the temp reached 237 F on the scanner. The cooling fans started running on low speed at 237 F and then stopped (10 seconds). I unplugged the temp sensor and both fans ran on high speed. Why does the computer tell the transmission to go into "limp" mode and start harsh shifting? Is there a sensor that is picking up bad information? The vehicle runs great in cooler weather.

[@Vacationtime247]

+alvinspmn The transmission is trying to save itself from burning up, this is why it goes into 'limp' mode. Do a pressure test of the coolant system and check for leak down. If it does leak down, listen for a hiss or water / coolant coming out. Sorry to say this, but these 3400 engines have a bad reputation for blown head gaskets. VT247

[@drivemode24.73]

I have a 3100, it has no problem turning over but at the same time it vibrates roughly, any thoughts on what it might be? Thanks

[@Vacationtime247]

+The Lopez Way Check your spark plugs and do a coolant pressure check. VT247

[@monasadventures2868]

New radiator could it be a head gasket

[@ahmaduhhs]

Great video, Thank you. Any videos of the spark plug replacement. I am at 105k.

[@Vacationtime247]

Front spark plugs are easy to get to. The back ones, take out the bolts holding the front motor mounts. Rock the engine forward and hold with a ratchet strap. They can then be accessed from the top. Or, raise the car and put on jack stands. Get under the car and go from underneath. Going from underneath is actually easier. VT247

[@hugh3rdof5]

@@Vacationtime247 I've watched this video several times over the years, with growing appreciation for you here, as I've been battling more and more of the chronic, nagging issues with this engine on a 2000 Montana. You've obviously dealt with so many of these issues, and only wish I could learn more from your experience. (?) Fascinated that you've apparently managed those notoriously hard to get at back three plugs so easily...... (would luv to see a video of that!? ) Have had similar nightmares finding leaks/cracks in the "rats' nest" set up of heater hoses and brittle 3-way T's.... (plus a hidden feeder pipe to the set-up that comes loose. Yet curious you mentioned the intake gasket itself could be the source of the hidden leak!) Even more interesting to me is your guidance to take care of the head gasket same time as you handle the intake manifold gasket. Makes sense, but I am startled by your breezy suggestion that the job is rather easy. ? You mentioned you'd be posting other links / resources for this multi-gasket job, but do not see anything? Any help?

[@hugh3rdof5]

Ah, found what you may have had in mind, links to your own two part video on changing these gaskets. Pt. 1 here.... (will no doubht watch this several times before attempting on my Montana....) kzbin.info/www/bejne/bKuanGqZatt_rLs