Newbie needs a definition

[Untamed]

What does the term "seized engine" mean? Obviously it won't run, however I'm curious to know what the conditions are that makes a seized engine. Is there a way to repair such an engine?

Thanks.

[Tru2Chevy]

Usually a seized engine has bearings that are shot. Once these bearings start to wear, they don't allow the engine to turn as easily, and eventually it won't turn at all.

Normally these can be fixed. Depending on what bearings seized, you will prolly need to have the rods looked over and resized or replaced, the crank will need to be cut or replaced, and a full bearing kit will be in order. Lots of other steps to a successful rebuild, but that should give you the main idea.

- Justin

[Fasterthanyou]

There are a few different things that can happen.
What Justin was talking about is one instance but I've found the more popular seize to actually be that of the rings in the bore. This happens when you overheat the engine so much that the pistons expand and the bore expands together closing the gap on the ring causing huge increases in friction and an interference fit. The easiest way to fix this is to remove the spark plugs and squirt a little oil in, then with the plugs out, turn the crank backwards until it's breaks the rings off the cylinder bore. Then keep rotating it a little. Next remove dizzy, prime the oil system up good and try and start it up.
When a rod bearing is shot really bad things happen. The rod usually friction welds itself to the crank and the resulting mess is a damaged block, crank, rod, etc. When a cam bearing seizes things aren't nearly as bad but the engine will need to be taken all apart to get to the cam bearings which are pressed in. Then you've got the main crank bearings. Those seize and you'll need a new crank or at least have it checked out and polished, then the block should get align honed.
Also when a bearing seizes you need to find out why before you go replacing the bearings and throughing everything back together. There is usually a clog somewhere in the oil passages. All it takes is a good overheating and you can spin a bearing, that's why tolerances are SO important when blue printing.

[foff667]

or in some cases a rod just lets go and bashes the head and then wedges itself against the crank so the engine wont turn over any longer

[Untamed]

Sounds difficult to work on and expensive to have done. I hope thats not my problem.

[9secfirebird]

moral of the story. if the motor doesnt turn over, its seized. most of the time its due to lack of oil and then the bearings get so hot as does the crank that the essentially weld themselfs....to eachother. its not your problem.