Technical 235 engine seizes while cranking

Hello, I’m hoping someone can help me with the following issue. I have a 1957 GMC truck with a 235. While trying to turn the truck over, it seemed like my battery was dead (freshly charged). I pulled the leads off of the battery and immediately removed the plugs, then tried to rotate engine by hand. Nothing. With all my force I was finally able to turn it by hand. I then tried to fire it up again, seemed like it wanted to fire but the same thing happened and it seized back up. Fluids are good and truck was running decent before winterizing in October. Any recommendations on what to try next?

I might as well kill two birds with one stone and ask another question. Last year while the truck was running, the exhaust burns blue smoke and oil-like condensation drips from the exhaust. Is this normal for these old trucks? I bought the truck in October of 2018 and before that, the truck sat untouched for about 15 or more years.
Thanks in advance!



Sent from my iPhone using The H.A.M.B. mobile app

 

When the engine is cold, you can expect some soot and condensed water vapor (which is a normal part of exhaust) from the tail pipe. Blue smoke generally means the engine is worn out, it's burning oil.

The camshaft gear can break and skip time, when it does, the connecting rods hit the camshaft, and the engine locks up. But there could be something else wrong with it, also.

 

Check the valves to see if one is stuck open. 235's have a weird valve combustion chamber arrangement and valves hitting the pistons are an issue (especially if the head has been milled)

 

Time to pull the pan …. there's bearing problems down there.

 

Damage could be done, but I'd pull the plugs again and see how it rotates via started, kinda had to turn a 235 over by hand, you must be grabbing the belts? Or was the crank drilled for a bolt?

 

When the cam is out of time the connecting rods will not hit the camshaft. With the valve timing off the engine will not start however. It might cough sometimes and act like it wants to start, because the valves aren’t open and closed at the right time in relationship to the pistons

 

It is cold in Saskatchewan today and is it 6 volts? How thick is the oil? If it ran when you parked it in October, I'd be surprised that something broke or whatever while it sat over the winter

 

Could be a light film of rust in one or two cylinders that had the valves open during storage. I'd pull the plugs, add a little bit of oil to each cylinder and crank with the starter. And, be sure the battery is charged, cables are good, connections at both ends are clean and bright. Let us know if it starts. If not explain how you are turning the engine by hand. "hard to turn over" means different things to different people. For instance, if turning using the fan blade as a handle, using all your force may be normal.

 

It’s been parked in a heated shop for the winter and it has 10w30 oil in it. Its a 12v system. I’m hoping nothin broke, I would also be very surprised!


Sent from my iPhone using The H.A.M.B. mobile app

 

I had one that a mouse built a nest in the bell housing. the ring gear was so rusty it swelled and locked up the starter.

 

Hey ken, in the past With the plugs pulled and using some force i could rotate by grabbing the blades. In this instance there is no give and seems “stuck” unless i really reef on the fan. Once i get it to move, it will move freely a couple of rotations and then it gets “stuck” again. Hope this helps! I’ll also try oil in the cylinders as you mentioned and let you know how I make out


Sent from my iPhone using The H.A.M.B. mobile app

 

Sounds like something is on top of one of the pistons .
You can force it loose and then after a coupe of turns it stops again .
Maybe a rat nest,,,they can get in places that nothing else can .
Or they built a nest and it was sucked in while trying to start the first time recently.
When I removed the intake from my Flathead,,,,it was a solid pile of cotton in the tappet chamber .
Good luck .

Tommy

 

lets see, ran when parked, bearing going out while in storage? not likely. timing gear break when first trying to start? possible, but not likely unless something else caused resistance to spinning. something not man made like mouse nest, or head gasket weeping into a cylinder. i would look in the cylinder with a bore scope, and see that the dist rotor is still point to number one when on TDC. you gotta get it to turn by hand before trying to start. i would think a rod hitting the cam would be a very noticeable crash.

 

Maybe you can pinpoint the cylinder with the issue if you watch the rockers while your turning the engine by hand. Of course with the valve cover off. At the same time you can see if all the rocker arms are moving. Do you have small visitors in the garage, during the winter, seeing it is a warm place in the cold white north? Tommy could be on to something.

 

I'd still pull the plugs and hit it with the starter. But I have age on me, not real patient.

 

It happened to a 235 I got from a friend years ago. It just quit running one day, locked up. He replaced it with something else and gave me the engine. I took it apart, the rods hit the cam and stopped it cold. Had a broken fiber timing gear on the cam.

 

Sounds like a possible happening to me.
Especially if you experienced it firsthand.
I know Jim is always right on the money with the Chevy stuff !

Tommy

 

If it only "locks up" once in every two revolutions, that pretty much says the problem is something that occurs only once in every time each of the six cylinders completes the four stroke cycle. To check Squirrel's suggestion bring #1 cylinder to TDC on compression and see if the distributor rotor is pointing to #1. Then rotate the engine and see if the rotor turns with the engine rotation. When the engine hits the "lock up" point that will also tell you which cylinder is causing the problem. (If the gears are good and in time.) When you have #1 at TDC drop a dowel (or other suitable object) in the spark plug hole and measure the distance to the top of the piston. When it "locks up" you can use that to measure how far down in the hole the piston is on the suspected cylinder.

If the problem occurs once per revolution then it says that the problem is rotating assembly related. When it hits the "lock up" point, chalk mark the balancer and count the turns in the reverse direction, rather than forcing it past, until it locks again. As you are turning it check the rocker arms for a loose one that would indicate a stuck open valve. If you think Mickey and Minnie were cohabiting try blowing air in through the spark plug hole. Some fluff should come back out. If air comes back out through the carb or exhaust that would indicate a stuck open valve. I don't think I would use the starter until I could turn it freely by hand. You could also drop the dust cover off the bottom of the bell housing and take a look there.

 

The starter is good??

 

I agree with X-Cpe ,
Every other revolution sounds cam timing related doesn’t it .
It also points to Squirrel being right .

Tommy

 

It also points to Squirrel being right . Again!!!

 

the odd part of the equation is that it seems to lock up slowly if i am understanding correctly. which at first thought would be just too weak of a battery or starter, but then he says "took all my might" to turn the fan blade after lock up. i like the cam timing thoughts, but then why does it happen slowly? hard to turn on a previously running motor in my world has always been either rust in a cylinder, or a stuck valve, or a mouse nest in the clutch area, however all those symptoms will get easier once it has been turned a few times. so, i'm stumped and we need more input from the op.

 

Thanks everyone for all the input and suggestions. I’ll be digging into the issue a little more this afternoon so hopefully I can report back with a pin pointed problem


Sent from my iPhone using The H.A.M.B. mobile app

 

Alright so I haven’t taken the valve cover off yet. But I have all the plugs pulled as well as the dist cap. Watching the rotor while spinning the fan by hand, there is no pattern on when it gets stuck. Sometimes it when the pistons up, sometimes when it’s down, sometimes different cylinders. Any thoughts on this?


Sent from my iPhone using The H.A.M.B. mobile app

 

Will it turn 360 degrees ? When you rock it back & forth, does it go "clunk"?

 

It will rotate 360 degrees. There’s no clunking when I rock it back and forth


Sent from my iPhone using The H.A.M.B. mobile app

 

My first thought is valves are sticking. Marvel Mystery Oil is your friend if that's the case. After verifying the valve and ignition timing is where it should be and nothing is interfering with the flywheel, clutch or starter or a seized up water pump, or anything on the front of the engine, pour a cup of MMO down the carb and spin the engine with the starter, it may get the valves working again....been there, done that. Good luck!

 

Valves could be stuck on several or even only one cylinder.Take valve cover off......remove rocker shafts with rockers......tap on top of valves with soft hammer.......spray/squirt light oil in around valve springs onto valve stem.....tap all valves again. I have had to do it on several 235 engines in storage over the years. Have fun.

 

any different when you try to spin it with someone pushing the clutch in?

 

if the valves are stuck, then usually once they get pushed open, (hard to turn motor) then they stay open until you do something about it and the motor will spin fast and easy with some dead holes. is the motor fresh with tight guides, or got some miles on it?