How to Tell Car Thermostat Is Bad (Symptoms of Stuck Open Stuck Closed and Overheating)

[@jasonmariani1258]

He did say basically a ton. But I totally understand everything he’s saying and he’s 100% correct. I give a damn how he translates the information. Basically you people should be grateful he’s sharing this info with us

[@robertkeene6097]

Exactly what I was thinking man! People are so petty and obviously on here for funny comments and not information

[@jaydenmartens]

This guy is basically the best for vehicle problem solving.

[@Rolls....Royce....]

Basically

[@georgetrowe8669]

Basically

[@big_time_2023]

This is the first time i hear about the link between the remp. Fluctuations and thermostat stuck partially. I have been looking for this in many videos but i only found this information in here. Thank for much. 😊

[@josephamati8572]

This is a very informative video within a short time. Thank you for sharing

[@stateboy80892]

Brand new thermostat installed!!.... Engine is at normal operating temperature but lower radiator hose still cooler than the upper radiator neck to engine coolant hose.... New radiator, upper and lower hoses and clamps too! Bled the system of air and still have the issue of that lower hose being cooler even at normal operating temperature!

[@CLIFFWILKES]

Having same symptoms what you do to fix

[@edwardsoma]

@@CLIFFWILKESi have the same issue with my 2014 Avenger 2.4L. Any solution?

[@CLIFFWILKES]

@edwardsoma yes after months and months come to find out it was my oil cooler that was clogged it was on a 2007 chrysler 300 3.5, there were coolant lines that run threw the oil cooler, and the crazy part is I had to tell a Mechanic. Because he couldn't figure it out. It made me. So angry Because I paid him thousands of dollars. To just get everything else wrong. I only figured it out because I decided to just buy the book and study. In meticulous detail. Hopefully you get it going.

[@mdmcpheron1]

See video above.​@CLIFFWILKES

[@marvinmurakami8828]

That means your coolant system is working properly. Coolant flows from the top to the bottom. Hot coolant enters the radiator from the hose at the top, flows down and is cooled by the radiator fins, and exits the hose at the bottom. This is also the reason the bottom radiator hose can last two or three times longer than the top hose.

[@needmake]

Great explanation I was thinking my thermostat was stuck on cold or partially due to some minor fluctuations but the test with the heat confirmed! Thank you for your expertise always

[@Top5AutoRepairs]

Glad it helped

[@alexanderbankowski5617]

Great video. Since you shared a lot to help me, from one salesman to another I'll share one too. No more "basically". "essentially" is way better. - Loan slinger

[@ZERONEINNOVATIONS]

Is it possible that the thermostat stuck open and not throwing any codes like p0128? My coolant temperature stays around 50c-60c. I opened the radiator cap, and started the car from the cold. I can see the coolant is flowing inside the cap hole. After driving on highway for 30 mins, it's still at 50-60c. I can even touch the running coolant inside the radiator cap hole.

[@fencersaber629]

You truly are a great mechanic

[@robertkeene6097]

❤ very informative and to the point thank you so much man! You nailed it

[@franckjoseph4806]

I got a 2000 toyota camry and i have the common sign which is the temp fluctuations like you said , the temp gauge goes high and low while driving . So i guess the thermostat got stuck open cause my car doesn’t heat properly and in winter time , when it’s very cold , the heat doesn’t work properly so i’m cold sometimes on my car. So do i need to change the thermostat?

[@Top5AutoRepairs]

It's definitely stuck open

[@Top5AutoRepairs]

So go ahead and replace it

[@franckjoseph4806]

@@Top5AutoRepairs ok thanks a lot

[@hapio1307]

No; send it to Donald Trump! After all this explanation you are still asking this kind of question.

[@franckjoseph4806]

@@hapio1307 you’re stupid, i have to make sure if the thermostat was really the issue. You don’t know sometimes it’s not the thermostat , you got the heat core that can be broken too. Don’t post a nonsense comment when you don’t know nothing.

[@nataliesimpson3892]

My 2019 Altima was running cool and my heater wouldn’t blow warm/hot air, with check engine light. But, my mechanic didn’t diagnose it. Now the temp is fluctuating, and it’s having a rough start with smoke, sometimes dies and have to restart. It still runs smooth, once it warms. Just wondering if this is most likely the thermostat, and if the rough start could be from too much coolant? Also, is the thermostat change out the same in the 2019, as it is in a 2018? I can’t seem to find a video for a 2019/2020.

[@lawwdogg1digr]

Also, if you have no cabin heat and your engine is overheating it is a sign of a thermostat stuck closed.

[@blazer3552]

Thank for your educational video. It helped me troubleshoot possible causes for the P0126 fault code.

[@BrianDalton-q4c]

I have a 1993 Chevy S10 pickup and I have no heat in it I clean the heater core would that be the thermostat then

[@fencersaber629]

Thank you so much the part.What you said the thermostat is fluctuating.That's what's happening to mine

[@JSavage_]

My thermostat is stuck open I guess because I’m only getting cold air coming. I gotta replace it ASAP because I’m freezing on the way to work. Thank you for the video

[@FunkyGOB]

I have a stupid question. Just did head gaskets on a 2010 dodge Dakota 4.7L. Got it all back together, topped off coolant after letting it run to bleed air from the system, and it’s been overheating ever since. We replaced the water pump gasket, the water pump spins fine with no vibration or chatter so the pulley bearing and fins are good. Replaced the thermostat and housing gasket. Vacuum tested the system and it held at 26inhg for over 5 minutes. Still overheats. Found out about the infamous 3.7/4.7L bleeder plug on the top of the timing cover where the upper radiator hose attaches. Had zero bubbles come out until the truck almost hit the halfway mark on the temp gauge so I’m not sure if they were air bubbles stuck in the system or just bubbles from the coolant starting to boil over. Heat works, engine runs fine, no misfiring or sputtering like it’s struggling to stay running due to overheating. No check engine light, no leaks, no smoke. Upper rad hose gets hot but lower hose is cool to touch even after needle crosses the halfway mark. So do you think I have a faulty thermostat (a Stant advance auto parts model) or am I missing something here? Oh yeah and it has a new Radiator and cap as well.

[@jrock865]

if the bottom is cold and not slightly warm every now and then then ya t stat is stuck closed.

[@jrock865]

take the t stat out and boil some water to the temp of the t stat 82c whatever your tstat is rated for and put a temp gauge in the water drop the t stat in and see if it opens or struggles opening. i went through 5 bad t stats from the store till i found a good one hope that helps.

[@jace9158]

So my ? Is I have an O2 Toyota Sequoia and today as I was driving my check engine light came on and Auto zone said it was my engine coolant temperature but my heat works good and wasn't going hot and I. Can also squeeze my radiator hoses .also I have 281k on my vehicle and in. The pass my check engine light will come on but go away over a week or few days so kinda wondering what it could be

[@MAGANATOR666]

If you put weeker springs on a thermostat would open up with less heat or faster? How would I design one to open with less heat? I'm doing an experiment thst is not automotive related?

[@lottawork631]

Basically, this was very helpful! Thank you.

[@MrJohnnyDistortion]

😂

[@robklempable]

"Basially"..."Basially"..."Basially"...good info basially

[@JacobEcret]

Bassly

[@abbasmuhsen2715]

Thanks for sharing this video Is it Wright when thermostat stuck open means increasing fuel consumption ?

[@Top5AutoRepairs]

That's correct

[@mhjsgjuyeavs1569]

Can that course it to run rough as well

[@mhjsgjuyeavs1569]

Mine runs fine when cold but in 5 minutes it runs ruff but it's not hot

[@trump4ever508]

I remember you from welcome back carter....we tease him a lot cus we gottum on the spot welcome back

[@SeriousPinoyGamer]

Thanks. Do you happen to know if it's okay to use coolant flush to clean the system after replacing the thermostat? I'm planning to replace the thermostat and the radiator hoses then flushing the cooling system before I put in new coolant.

[@Top5AutoRepairs]

Yes you can it shouldn’t be an issue.

[@big_time_2023]

Replace the hose after flushing i guess

[@donmagic2002gd]

At least he knows what he’s talking about 👍🏽

[@OfficalPrinceToni]

Basically you both are right

[@davianceable]

Partially open section is what most people doesnt mention ,my thermostat was like a new but it was partially open and close cant fully open itself ,ı think is if its clean or rusted no mattar what change it every 5 years or 7 years max.

[@dalegribble8140]

When the thermostat stays half open it is called a lazy thermostat. You can test the thermostat showing it opening but Doesn’t still mean it’s not lazy

[@tomdexterparaguya1964]

Is thermostat are repairable?

[@netflooder263]

​@tomdexterparaguya1964 it's replaceable, it depends on the car how easy it is to replace

[@NemanNik]

back in the summer my toyota corolla 2005 temperature gauge would go up and down after engine warming up and now in winter the gauge wont go to middle and heater take like 30 minutes to barely blow any warm air and for hot air it takes like an hour .tnx bro i will change the thermostat

[@Hidriz]

how much it cost to change the thermostat?

[@NemanNik]

@@Hidriz it costed me 6$ cause i live in an asian country so iam sure it will cost u 20x more

[@johnnyversaci7091]

@@NemanNikdid that fix your problem? I get overheat sometimes, sometimes ok I think I will change thermostat it has 243k miles haha

[@NemanNik]

@@johnnyversaci7091 i used to put just water in the cooling system and that rusted the thermostat was jammed in close position so yeh it fixed it

[@johnnyversaci7091]

@@NemanNik ok cool mine overheats sometimes but then temperature goes to normal, also the heater takes a very long time to work sometimes

[@flolou8496]

??? Do you check for codes with a scanner with the engine running right away or do you wait 10 minutes while it's in park than check for codes? My link appears to be coming closer to the surge tank area and not the thermostat area, but who know,s maybe the way coolant flows it just leaks closer to that area, but I would like to rule out the closed thermostat/bad thermostat idea, I just don't know what type of codes I'm looking for either or which scanner tool is best?

[@TheDavit16]

No garage has been able to work this one out! VWTouran 62, after both thermostats were replaced by dealership (because of overheating issues )afterwards I now have underheating issues! The dash temp guage sensor has been replaced. Still the guage fluctuates up to 90c n back down to zero. Oil is 50 to 60. And not much heat in cabin. Tho it can stay at 90 and oil at 100 and good heat in cabin. Each time I drive the car I do not know what to expect because its intermittent. Water pump has been changed. AA guy came out today as engine light showed. He was certain it is the thermostat but VW wont except it! I have no idea what to do next.

[@bosssanchez3247]

Change it yourself 👍🏼

[@TheDavit16]

I would if I knew how! Lol not forgetting Im a granny now not a spring chicken! 🤦‍♀️

[@Sr_iRL]

Lately the temperatures have been rising in Southern California, I have a Chevy express with the 6.0 and today while driving through the mountains I stopped for a bit on the side of the road and the temperature read 210 it used to read about 180 few weeks ago and it is usually at 190 more or less. Should I be concerned?

[@Top5AutoRepairs]

Yes if the temperature stays above 190.

[@Sr_iRL]

@@Top5AutoRepairs so I finally had some time to get my hands dirty and replaced water pump, thermostat, radiator, and fan clutch and my issue still persist. What else can I try? There are no leaks. Thanks

[@aaronmlller8150]

Flushing the system may help, also could be a coolant temp sensor issue.

[@Sr_iRL]

@@aaronmlller8150 thanks for the suggestion, I actually have replaced the temp sensor and the issue persists. I never saw the coolant cycling through the radiator which is leading me to believe that there is some blockage somewhere, I don’t know how likely that is to happen

[@SuperchiefApache]

@@Sr_iRLit happens more times that one would think!

[@2Nelly4]

So Basilly.. You are the best

[@stevenbean9706]

this is why the genious rocket scientist that engineer these cars should put two tiny bypass holes in a thermostat so you never ever have to worry about overheating! i dont even use a thermostat i put a small disc in with a tiny hole that keeps my car running at a constant 180 and never will i ever have to put a thermostat in

[@HellZell99]

Can you do a video on how to install it on an Acura TSX 2009

[@Saint696Anger]

Great channel man 👍👍

[@FoxNewsNewYork]

Thanks. You explained this well.

[@hellohello8556]

My thermostat is stuck open on a 2004 Kia Pregio Diesel with no EGR or dpf. I can't afford to fix it until next week. My question is will it damage my engine if I drive for 30 minutes a day at 60 kilometers per hour until I can afford to fix it?

[@Top5AutoRepairs]

It will take longer for the engine to warm up. In the short term it will be fine. Just make sure to replace it when you can afford it.

[@hellohello8556]

@@Top5AutoRepairs Thankyou for your reply it is much appreciated. Will do as you recommended.👍

[@zoovaj0013]

Keep it up brother

[@youknowcrimedontpay9257]

Very good video. I'm subing

[@marksreef3321]

Basically good information… 😅

[@Daddyrabbit_2]

That comment was basically pretty funny 😂

[@chadcovey1626]

Basically

[@Daddyrabbit_2]

@@chadcovey1626 your basically killing me🤣😂😅

[@elizajane91]

English 2nd language individuals use basically a lot. It’s taught as a form of “um”

[@jacobgregg6966]

Big help. Thank you so much!

[@cspill99]

I have a 2006 Chevy Impala. Hot Engine symbol on cold startup, as the car warms up it goes off. Is this my temp. sensor or the thermostat?

[@MrSwish702]

I believe it's a sensor

[@liljeff39]

Would the heater core also blow cold if the thermostat is stuck closed?

[@Top5AutoRepairs]

It will blow hot and the engine will overheat

[@liljeff39]

Ok thx.

[@Sk8orDieWorldWide]

My fans won't come on when they need to. Occasionally I will get just the A/C fan but at a lower speed and the regular fan kicks on for a second then turns off. Same after ecu reset. If I jump the sensor/switch on the thermostat housing BOTH fans come on very strong. I noticed my iacv is leaking from the middle gasket also. When I leave the cap off and start the car, the coolant eventually starts to boil and thats when I notice reservoir going low. Any ideas what this can be? I purchased an OE thermostat a month ago, along with all fan switches. Relays are good.

[@icebeezyent8757]

Did you change the coolant temp sensor?

[@Sk8orDieWorldWide]

@@icebeezyent8757 turned out to be the sensor on the thermostat housing. New one was bad. Used my old OEM one it works like a charm. All my sensors are new except this one.

[@danlford]

So if my thermostat is stuck partially open it would run at normal temps while idling but run hot while driving because the flow is not enough since the thermostat won't open fully? Please tell me I'm right.

[@FickeyH]

Good info 👍

[@diazedvin04]

@top5autorepair any idea why the heater keeps blowing hot air by the vents even though the heater switch is off please any thing would help I need to fix this since is summer in Arizona

[@Top5AutoRepairs]

The blend door is probably stuck. Check for faulty blend door actuator. It's located behind the dashboard and glove box. If you pull random blend door cable it might change the position. GL.

[@diazedvin04]

@@Top5AutoRepairs I appreciate you brother

[@sevenLP]

Hi. My NOTE 1.4 PETROL has an issue that everything is ok for the cooling if the temp is up to 95C. If it goes over, due to higher RPM, the temperature start rising and the temperature only goes up. No coolant leak, no bubbles in coolant on idle, no oil in coolant. No codes on OBD. Any idea what could it be? Thanx for any help.

[@maxswp]

My temperature gauge has been rising only while in park after driving for a little. It goes up to between 1/2 to 3/4 but when I drive again it goes back to normal. I just had a heater core replaced for leaking coolant from behind the glovebox and it was smelling from the vents. That has been fixed but now I’m having temperature problems while in park. I wonder if maybe something wasn’t put back properly or if I have a bigger problem now?

[@grandam]

Make sure you don't have air in the cooling system

[@lofty24g]

May have to change mine by looks of it. Was originally told my hearer core had blocked up so i changed that but im still not getting any warm air inside the car. Pipes to the heater core are warm, the hearer core itself is hot but still no hot air been blown into car. It blows cold and slightly gets warm when driving but nothing more. You think its the thermostat thats the issue ?

[@WESTSIDEZ4]

I have this same issue. Now the temp gauge is starting to rise as well. I’m just gonna change the thermostat

[@joepatterson3925]

I just bought a 02 acura mdx and it runs at normal temp but blows cold air could this be a bad thermostat

[@Top5AutoRepairs]

Thermostat is either stuck open or heater core is clogged

[@OffTheSkooma]

Hey so my car overheats after sitting idle for awhile but on freeway it under temp and cooler by a bit and it takes a bit for my car to hit 180 on my gauge will a stuck open thermostat cause that? I changed everything my radiator my fan my thermostat my water pump and I’m still getting hot idling like if I did virtually nothing.

[@iblessking650]

did you figure out what the issue was?

[@OffTheSkooma]

@@iblessking650 yup the previous owner installed the water pump with rtb all over all Willy nilly; there was rtb in the water pump jackets; blocking a lot of the coolant from getting in

[@labi.not123]

I have a question, and it would be very helpful if you had time to answer. My volvos temperature is not reaching the correct temperature when idling, but while driving the the temperature is in order. As soon as i stand still while the car is running- the temp is dropping. What could this be? Thanks

[@im-that-guy-pal]

Waterpump

[@labi.not123]

Thanks for the response You think is water-pump not open thermostat??

[@martymartin2894]

Mine is opposite, it's only hot when idle but gets cold when driving. What is this.

[@labi.not123]

Check temperature sensor or the fan

[@martymartin2894]

@@labi.not123 ok thanks.

[@BillyBarus-x3x]

Basically, well explained

[@13pepsicolas]

So I have a question, my heat will not work on the 3 lower settings but will blow on the highest for 3-5 minutes then kick off. I’ve replaced my blower motor resistor and my blower motor fan works, what could it be? Must I add my car isn’t overheating at all, and it gets up to operating temps just fine

[@user-2Hteyasizyc]

Im sure you don't have a blower motor resistor hahaa

[@ericksanchezHN]

Mine had a weird behavior, it was never reaching normal temperature (it was in cold) and the engine was warm, then I park and when the gear was moved to P, suddenly changed to normal temp, also when I changed from AC to heating knob, it changed to normal temp again

[@martymartin2894]

I have same problem, what was ure problem please tell me.

[@xzavierguerrero4982]

So my temp gage goes from super hot to regular tempatures and keeps moving .. that means it’s partially open? && does it effect the heater in the car ?

[@Top5AutoRepairs]

Yes it can affect the heater. Coolant flows through the heater core.

[@marcusjohnson5319]

Hey my Nissan max is not over heating but my cabin is hot, could this be the thermostat, I just changed the AC clutch and a new radiator, it still blowing hot air.

[@carlosmuler4773]

Very interesting and helpful information.

[@charleshenderson9375]

Quick question if you don't mind. Will overflow tank bubble and coolant drain if it's the thermostat?

[@rcparts3d893]

thats likely a head gasket leak

[@reluctantgamer3879]

Hey my 520d F10 sits under the centre of temper gauge just little bit to the left is this normal?

[@MiguelEscobar-l3d]

What if I changed my thermostat but the thermostat went bad again ?

[@billybobbarker3175]

Change it again. It is unfortunately common for new thermostats to fail too. New stat failure rate I have experienced is 30%.

[@shawndread2899]

No overheat but check engine light on and scan reads thermostat housing for a 2019 Jeep Cherokee limited

[@chrishall8222]

Will it create noises around the thermostat housing

[@yasharshachaawar5530]

Good info man

[@Top5AutoRepairs]

Glad it was helpful!

[@elcompashuyy]

Wha could be the cause of a car overheats when hot outside but not when cold?

[@sksupply]

I have a 2000 Isuzu Rodeo that overheats. It melted the radiator cap, so I replaced that, but its still overheating. NO heat when turning on the interior heating floor/vents or defrost. Has a new radiator and no coolant leaks. Thanks

[@ogtiddyclapz4055]

Did you check water pump

[@draco_tv_letsride]

If the thermostat is stuck open, is it possible that the transmission will overheat due to the fact that the cooling fan will not going to turn on due to that the coolant sensor will not trigger the ECM to turn on the fan? Is the transmission oil cooler cools itself because of the radiator fan?

[@taco9265]

Yes with a stuck open thermostat you will notice your trans temp rise when sitting/stop for to long because of your fans not kicking on

[@Figuereditout]

Will a 180 thermostat for my 7.4 454 Chevy good or go higher?

[@victoriatorres5334]

If my thermostat is stuck open should I replace the thermostat?

[@Top5AutoRepairs]

Yes

[@dakid_josh15]

So my rover took longer to heat up than normal and when I drove it it spiked up to H so what are the symptoms of that also it was blowing cold air

[@edwardsoma]

I have the same issue, did you find a solution?

[@laurachavezmendoza8706]

Hello from California I replaced my thermostat and I have a leak is it because I used no glue

[@damanypalmer5849]

Basically he said basically about 100 times

[@jeffreyalvarez7398]

17 to be exact.

[@BANE.-.]

Basically, I categorically reject that. Basically.

[@afghanj1381]

That's basically 1 basically every 7 seconds. Basically.​@@jeffreyalvarez7398

[@seanbyars5751]

so basically if i heard him say "so basically" one more time i was basically going to shoot myself in the head

[@jildonreyes8905]

Basically

[@atlantasamedaydelivery1769]

Great information

[@jimbomorrison7133]

Thanks very much.

[@jimbomorrison7133]

My tundra 06,4.0L always stays below middle of C and H. Now I got in it Monday and it won’t go past C,just barely. The radiator I can hold my hand on and the hoses. Couldn’t do that before. Running rough idle. Changed the coolant sensor on the block but same problem. Running very low idle and not moving from C. Just barely over C. Any help? Changed thermostat 3 years ago with coolant.

[@EnthusiastOwned]

My rsx recently got mildy hot but i turned the heaters on and they werent getting much heat at all so i turned the car off for 25 seconds and it went back to Operating Temp but the heaters rlly only got hot when i would actually drive

[@kalpeshkapadia4623]

Thanks sir

[@enrycabello5217]

I’m here in El Paso Texas. Can you pls come and check my 1999 Honda accord??!!!! 😂🥺V6. When I get home from a long drive . Fan stays on for minutes. And when I’m driving if it a long drive , temp gauge goes a bit up more than half where it’s suppose to be. Pls help me!!!!!!! Do I stop moving car and take to shop??

[@JB91710]

I have a 20-40-thousand-mile Subaru 6-cylinder engine that sat on a bench in an unheated or cooled garage in the Northeast for a few years with no antifreeze in it. When I ran the engine, the thermostat never opened. Could it have rusted shut or something else go wrong when it wasn't lubricated? Thanks.

[@SuperchiefApache]

Yes, thermostats can rust, get old, all manner of issues. If someone used water in that engine for cooling at one point, then it will rust.

[@shawnsweat4476]

have a problenm thermonstat is broken no center no spring trying to figure out wat r where did center go i just tok off all i have is round piece withe hump over the back but the hole center and spring is missing

[@Upnadem]

I have a 2010 b6 passat tdi, today while driving i realised my coolant temp fluctuating between 70⁰c and 90⁰c and when i opened the bonnet i saw what appears to be a leak from a hose connected to the radiator. Does this mean i have an open thermostat?

[@TIIRONC5H]

I have problem my golf 4 tdi gauge goes normal at midle 90 but i See engine is overheats And Fans not comes on i change sensor still dont comes on Only some times idk

[@rrosie20101]

Great video, thank you very much!

[@troyalaniz2886]

I’ve replaced the thermostat and it turned the check engine light of but the car is still stuck on cold my heater works fine and everything I understand it’s probably stuck open but not sure how to fix the problem

[@Jp_5ive3hree]

I have a 205 gmc sierra and I replaced the thermostat because the temps where up and down and heater wouldn’t heat, now heater works fine but I’m guessing the thermostat is stuck open because it won’t get to opperating temps and I got the p0128 code… I’m not sure what else to do because both thermostats worked when I tested them

[@markvermeulen1372]

Explain your “test” procedure. Details, details, details. Author a procedural process.

[@Amahyze777]

What was the fix?

[@Amahyze777]

Was it the thermostat?

[@spheth8895]

Thank you. Hopefully this is the fix.

[@stefanescumihai3638]

hello, what if my temp is not reacing operating temperature if i use the car heater?

[@Nolimitgang999]

Your thermostat is Stuck open/ partially open

[@sabinovazquez2235]

My 2017 Colorado temp fluctuates and is leaking when I park it

[@martymartin2894]

Hi can someone please help. I have a Peugeot 307 petrol and the temperature gauge for Both oil and coolant works and goes to the middle while sitting in idle, but soon as I drive the temperature on both gauges goes to zero and no heat in the car. If I park in idle the gauge and heat works normal.

[@Recklez_j]

Can this be the reason why the heater in the car doesn’t work anymore as well ?

[@BKNY1322]

Can I still drive with a P0128 code. My engine fan keeps running

[@hellohello8556]

Good video thankyou I subbed.👍

[@machtnichtsseimann]

I don't get it. My temp gauge reads around 170 F at its peak, no fluctuations in temp, now weird sounds, runs/accelerates smoothly, the heater works well ( hot ), but my check engine light came on for the code P0128 and fuel efficiency seems to have been worse lately ( it was already bad on a Chevy Express van! ). Anybody got any clues? Is it still a bad thermostat?

[@josephtanner348]

Perfect explanation

[@stevenhall9009]

This was basically a very informative video, basically speaking.

[@joshehman3571]

Thanks

[@stevewilliams1834]

check light came on 2016 Mercedes E-350 - but vehicles does not overhear, or take long to heat-up or reduction in Fuel economy - Garage tech scanned the engine and it thermostat. Just did a 1500 mile roads trip with no issues, How do you know the Thermostat is truly failing

[@Top5AutoRepairs]

Hello. Check the upper and lower radiator hose. Both should be hot when engine is warmed up. That's how you know the thermostat is functioning properly.

[@kentuckyking4343]

If I'm losing antifreeze and when defrost is open it doesn't overheat but if normal heat on it does overheat. Is that a thermostat

[@bosssanchez3247]

Same problem here

[@La19930]

So… Basially…

[@RoLE777]

Lmao this guys best friend word is basically

[@RobertMorris-l3l]

What happens when it only over heats when idle or if it's very very hot outside

[@FractalNinja]

Hmmm check the radiator fins for excess dirt/dust/bugs? If the fan cant blow cool air over the fins it cant pull the heat from the coolant. They got some A/C cleaning foam that will bubble and scrub between them for you and then rinse it out and hit it with some compressed air from the back side to blow out anything left behind. Hope this helps.

[@EfrilArgete-w6g]

Why the radiator of vios gen 1 reduces water even if no leeking is the reason