what causes an engine to seize up?

[ForMySon]

Getting ready to pull a semi-seized up sbo 350 block and attempt to rebuild it. It will start and run with a low deep knock then it will grind to a halt after bout 3 minutes. It hasn't been started in 1 1/2 years.

Just looking for a simple list of possible problems and maybe a few solutions.

 

[Dr. Rudy]

how many times was it allowed to run until it locked up? Check the oil and make sure there actually is oil in there, because if not then you are looking at a lot of replaced parts.

 

[hurst1979olds]

how many miles are on the engine? What kind of oil pressure does it have when its running? For the overhaul, Id have the block bored and honed. I would definatelly have the crank ground. I would even have the connecting rods resized. New bearings for undersize, pistons(due to over bore), NEW Oil Pump and gaskets you should have a solid shortblock again.

 

[1983regal]

Getting ready to pull a semi-seized up sbo 350 block and attempt to rebuild it. It will start and run with a low deep knock then it will grind to a halt after bout 3 minutes. It hasn't been started in 1 1/2 years.

Just looking for a simple list of possible problems and maybe a few solutions.

If you want to keep from damaging the block and internals stop staring it with the knock, its time for a rebuild. I had a 69 chevelle knew something was wrong but couldn't tell until we tore the motor apart, was a loose center main cap. It ate the register out of the block for the main cap, was a large journal 327 block which was scrap afterwards.
Only solution is a rebuild you can't fix a knock any other way, a knock is something loose inside the motor. Now if it was just seized from sitting you can pull the plugs and either put a little trans fluid or lucas oil in each chamber and let it sit a day or two, then turn over by hand until it moves freely then make sure you have oil pressure and start it. This method will cause it to smoke until it burns the fluid you put in the chamber, usually about 30 minutes will clear it up.

 

[chevy2480]

Any number of things could cause it to sieze. But by what you describeing i would bet you have coolant leaking into a cylinder causeing it to sound like it knocking due to compressing fluid. And after a few minutes of running cylinder fills to the point where it can no longer run.

 

[hurst1979olds]

Any number of things could cause it to sieze. But by what you describeing i would bet you have coolant leaking into a cylinder causeing it to sound like it knocking due to compressing fluid. And after a few minutes of running cylinder fills to the point where it can no longer run.

Water/coolant does NOT compress. If you get water in the cylinder it will not compress and it will always break at the weakest link. Bent rod or broke rod. Its called hydraulic lockup when water enters cylinders.

 

[chevy2480]

Any number of things could cause it to sieze. But by what you describeing i would bet you have coolant leaking into a cylinder causeing it to sound like it knocking due to compressing fluid. And after a few minutes of running cylinder fills to the point where it can no longer run.

Water/coolant does NOT compress. If you get water in the cylinder it will not compress and it will always break at the weakest link. Bent rod or broke rod. Its called hydraulic lockup when water enters cylinders.

You are correct my friend but a small amout of coolant will cause a hammer effect on bearings causeing a knocking sound and motor will run. Been there done that. Was suggesting exactly what you where saying motor is running until it hydrA locks. A motor with this problem will eventually start back up after awhile if cly drains past rings. Once again been there done that. I not f'in stupid i know coolant wont compress but a small internal leak will alow a motor to still run up until it hydralocks in the mean time it causeing all kinds of noises. I have been building and blowing motors up in many different ways for the last 18yrs. It was just a suggestion.

 

[megaladon6]

this is the situation where there are too many possibilities and no good answers. tear down the block, check every bolt hole, bearing, rod etc. i would plan on a full rebuild, just to be safe.

 

[chevy2480]

this is the situation where there are too many possibilities and no good answers. tear down the block, check every bolt hole, bearing, rod etc. i would plan on a full rebuild, just to be safe.

Exactly. As stated by me before it could be any number of things. I would do exactly what megaladon6 suggest tear her down and plan for the worst.

 

[pontiacgp]

what are you planning on doing, if it just a stock 350 you might get off cheaper buying a running motor to rebuild...just saying