One Short of a Six Pack - Diagnosing Cylinder Misfire of a 1961 GMC K1500 3/4 Ton Dually

[@williambasinger5859]

Ok Terry I have two of these engines v6 305, and about 43 years of turning wrenches for dealerships. So here is what I’m going to tell you. The intake on the number 2 cylinder was stuck open for how ever long that truck sat for and the valve got stuck. The seat and the valve face also rusted. So it isn’t sealing well. The push rod bent because of the stuck valve. So you freed up the valve and I hope you put in a new push rod. You can not preform a leak down on a old engine like that because it means nothing to do so. The tapping you are hearing is in the valve train because this engine is flat tappet and doesn’t have hydraulic lifters. It needs a valve adjustment. But more than one of the valves were open at the same time while it sat there. So you also have another valve that isn’t seated properly also. Now to adjust those valves you have to do it with the engine running. I would use a feeler gauge that is 4 or 5 thousands thicker than spec to allow those rusted seats to wear back in. Then after a few miles and things have settled out I would then set them back to spec. Don’t worry about the rings at this time just drive it, and put it through a few heat cycles and then if you want recheck the compression you may find things have greatly improved. If it isn’t burning oil then it won’t be the rings. Just remember that the valve guides (from stuck valve stems) can also cause the engine to burn oil also. Make sure when you change the oil to use real dinosaur juice a 15w40 truck oil like RotellaT. Also use a zinc supplement your valve train will thank you for that. I’m always looking for 60-63 gmc trucks they are my passion I love that big block v6 it is a true truck engine no speed demon but will stop the world spinning if you could find a way to get hold of it with a rope or chain, that engine is pure torque. Oh and by the way is isn’t a k1500 it is a k2000 black in the 60ies they were 1000 for the half 2000 for the 3/4 3000 for the one ton. And with the duel rear tires I would almost bet it is a k3000 with a 351. But it might be a 2000 with a 305. I have never seen a 3/4 duel rear wheel truck

[@stephensaasen8589]

I'm with you on that. I've watched alot of engine revivals and stuck valves are common. Usually best to pull valve covers and check for stuck valves. And like you said, you gotta run them for awhile and let the valve train beat the buildup out of the seats and let the rings free up and reseat before attempting compression tests or leakdown. Compression tests are only good for finding a dead cylinder that's still got spark or the thing won't start at all during revive and you need to see if the thing has enough compression to start.

[@HODGEPODGEDODGEGARAGE]

Great job with the diagnosis 🙂👍 Crazy to see it ran with the push rod off! 👀

[@commiehook6323]

I'm really enjoying the series on this old girl. Good work!

[@danielheartsill4269]

My vote is put the new push rod in, get the brakes, tires, and any electrical needing fixed. Many times on engines that have sat for years, junk builds on the valves, the rings are stuck in place. Drive it a thousand miles and see what condition you have then. I have seen on these type videos many times driving helps a lot of problems work themselves out. Good luck, it's still a nice old truck and better than you can buy new.

[@dodgefree1400]

I’ve worked on countless GM products but had to look that engine up. 305 60 degree six throw V6. From other videos it’s built heavy like a diesel. Very interesting heavy duty gas engine.

[@terryuland6502]

It's a monster. That coupled with 4wd low speed and the "low speed" rear end, the torque is out of this world. We've literally pulled houses with this thing.

[@wallbanger1968]

And a 478 V6 bolts in the same place.

[@dylansgarage1685]

Can't wait to see more videos on the truck!

[@terryuland6502]

I’ve got several more on the way!

[@shoelessb4515]

Leakdown : cylinder must be at top so both valves are closed. Use your dead blow hammer and Kroil to check for stuck valves. lube stems till the valve moves freely. Straighten that pushrod temporarily and readjust all valves. Don' t guess whats wrong.

[@evanwilliamson2418]

What an amazing truck! Just finished watching all the videos and excited to see more. subscribed.

[@terryuland6502]

Sweet! I've got a lot more on the way!

[@alexinnewwest1860]

Such a wicked truck. You start running that engine and those rings will re seat eventually, they get stuck in there lands from sitting so long

[@oviliaguilmette9424]

It wanted to live,a little late I know, just watching glad to see a neglected piece of history getting some tlc

[@SammyVista1972]

Terry, I am sure by now you have adjusted the valves, and tuned the engine up, as well as do a flushing as several here have suggested. You state your dad say the engine was rebuilt, the evidence shows with the later intake etc and missing exhaust manifold bolt tabs. Where I am going with this is that I feel with running for a while, especially once you get tires and brakes up to snuff, that 305 - 6 will run much better with the rings being freed up and the valves ridding themselves of dirt on the seating areas. Unless I am missing something, I heard no rod knock, your oil pressure is 25PSI idling at a very low RPM, who knows how diluted the oil is in there as you only added the three quarts to who knows what remaining in the engine. Looking forward to the updates.

[@thecollectoronthecorner7061]

The heaters in the GMC and Chevy trucks will freeze you to death. They take in cold air from the cowl at the bottom of the windshield. and circulate it thru that little heater core under the hood. Just a poor design. I would put duct tape over the cowl vent. and open the vent inside the cab to get it to recurculate the heated air. Helped a lot.

[@terryuland6502]

Honestly I doubt I'll do anything with it, as it's entirely likely I'll only be driving it if it's "nice" outside.

[@pochosousa4653]

Hermosa camioneta. Espero ver más videos de ella¡¡¡. Te saluda cordialmente un argentino desde España

[@stephensaasen8589]

I know it's been a month but I'm with William Besinger' comment below. I've watched a lot of revivals. Usually one or two valves stick. Bent push rods are a big issue on engines that have sat for many years. You may want to check for any more that are bent before adjusting them. It's usually best to pull valve covers before ever attempting to start or turn over engine, loosen rockers if possible and tap the valves to make sure none are stuck. Stuck valves are usually freed with penetrating oil and patience. You don't want to wrap on a valve very hard either and break a stem. And, yes, you just gotta run them for awhile before you do compression or leakdown tests. Let the valve train beat the old rust deposits out of the seats first for awhile. Change the oil often for a bit. They usually come around. That idle was so low it may have been knocking because the oil pump wasn't getting enough oil in the engine. Those old GMC V6 engines are strong runners! Maybe not powerhouses but good runners.

[@AndrewHCann]

Excellent video :) I remember those trucks a late friend of family had couple these trucks use show off those on farm I grew up on back to my late Dad and late uncle ran! Guy told me those motor called Hercules 4.7 litre 305 V6 and when first hear about them thought was getting joke about V6 because I fimlar with of 5.0 litre V8 305 was later motor GM did ! But these Hercules 4.7 litre 305 V6 Motor is same bore also stroke of 409 V8 minus 2 cylinders and never rebuilt one or drive that motor in 1960's GM pickup trucks ever ! But heard lots about them and amazing me to ! My high school Auto Mechanics teacher had explained about them V6 305 Cubic Inches size Hercules motor and got some students rebuilt motor totally put back truck to ! He said was short live motor in production line motor and one testing before made 4.3 litre V6 252 or 262 Cubic Inches size High Output in 1988 to present years! If want quick fix 305 V6 is on first clean Oil change and filter get Bottle of STP Total Treatment fuel injection and carb cleaner in fuel tank worth ! Also get a bottle of Gunk Engine Flush Fluid add in engine oil when change plus oil filter also run in motor for 5 to 10 mins be best on low idle and smell paint remover or smoke bad it clean up engine fully too to ! Then shut motor down drain plug out then let pour out till stops also put plug in but Don't tighten up yet do Engine oil filter too then put new on and then take drain plug out again see more dirty oil come out ! Then if all done put plug in and tighten also add engine oil! When first couple times start up see bit smoke and smell Paint Remover but that Fluid flush disappeared soon afterwards no worries just light clean more ! But tell you do Gunk Engine flush to old or new motor every 3 years think got brand new or fully rebuilt motor too in gas or deisel! Plus STP Total Treatment fuel injection and carb cleaner in fuel tank in deisel and gas motor save fuel troubles too also less fuel burning also excellent fuel mileage too ! Save lots $ money no kidding and be impressed! Even farm tractor running perfectly too on both Bottle stuff do and done to also shocked me on test my one guy Cousin told do he been Mechanics for nearly 50 years and I am in 25 years! So thought try help you out and others!

[@rayward3835]

Great Video! Keep up the good work.

[@bozodog428]

Pretty clean inside those valve covers. Might just need some marvel to free up the rings and valves. Had a 64 with the 305. Ran good but never had all that much pulling power and liked premium fuel. Maybe because of the large bore diameter. Much prefer the inline sixes from Chevy and Ford. Especially Ford's 300ci six.

[@kevinhines4240]

Say Terry good friend you got a gold mine here nothing like a classic truck that you feel good when you can and old treasure Life.

[@jackjacke4654]

I love that truck!

[@richarddavis3007]

Them 305 v6 are tough motors

[@bertgrau3934]

Throttle should be held wide open, or you get a lower reading. I seen bent push rods before too, straighten and worked fine

[@statenclayton4552]

Where are you located.... that truck is in decent condition

[@matts1972blazer]

Someone has had the head off or just the manifold off because it's missing nthe lock tabs and that's a aftermarket exhaust gasket, also the originally had a 1 barrel manifold someone put 62 -66 manifold on it, also these are flat tappet cams run high zinc oil

[@terryuland6502]

Interesting. It was rebuilt by a family friend in the 90's, and since you were looking at the exhaust manifold, did you catch the bolt that's not even all the way in? I'll keep that in mind about the oil.

[@dalehale1635]

Why in general would a head need to be flipped as you showed the block plates for coolant passage, I hadn't heard of that before and I may have missed it but what's the engine cubic inch size out of curiosity?

[@terryuland6502]

It's a 305 cubic inch engine. And I'm not sure, I just read that in the service manual that the heads are interchangeable.

[@dalehale1635]

@@terryuland6502 that's crazy that it'd be engineered like that. I also love the tank like ability of this truck and am looking forward to the charger video. I just subscribed today and will be checking your videos out for a bit! Thanks for the fun content!

[@jftureson]

I'll bet you a dollar a marvel soak and a good heat cycle will make those rings come around. Just blow the Cobb webs out! "Itilian tune up"

[@thecollectoronthecorner7061]

Those V6 engines are very expensive to buy parts for. Its easy to get a chevy bellhousing and convert to mechanical clutch linkage and swap in a Chevy I6 or V8. and get much better fuel economy. The V6 was Ok when gas was less than 30 cents per gallon but today there not viable.

[@terryuland6502]

Yea I've seen a lot of folks do that, but I doubt I will here, at least as long as this one runs. I won't be driving it enough for the horrible fuel economy to hurt -- and yes, this thing got like 5-6 mpg lol

[@skipstein744]

Onward!

[@larryippert8143]

run it it will get better

[@daveallen8824]

Road draft tube

[@larryippert8143]

I'll fix it.take rocker off and lube it and tap on the valve to open and close

[@johncatalano7185]

Might've been easier just to overhaul it altogether........

[@terryuland6502]

I've thought about that but the engine was overhauled "not too long ago" according to my father.. which was sometime in the 90's, but truthfully it doesn't have many miles on it since then. It's mostly just been sitting

[@michaelerickson1518]

No

[@greghansard2490]

😴