Posted by vince on Monday, May 29, 2006 at 10:26PM :
In Reply to: freeing a stuck motor posted by John S on Monday, May 29, 2006 at 8:21PM :
I've fooled around with old motorcycles for more years than I should admit. Many parts bikes have stuck engines, and the engine is not worth rebuilding, but is worth money as parts. Problem is, it's tough to disasseble a stuck engine without having to cut other parts.
First, try to figure out why it's stuck. Has it just been sitting in a barn for years, or does it possibly have internal mechanical damage, or has water leaked into a cylinder or two. Drain the oil out and see what comes out.
How have you tried to turn it over? A big cheater pipe on the crankshaft, or pulling? I'm always leery of damaging something else with too much force.
If it's an overhead valve engine, take off the valve covers and see if anything is wrong. Then check the spark plugs. Is one or more wet or rusty? My favorite way to check the cylinders is to use a Q-Tip taped to a plastic rod and feed it into the cylinder to get a sample of what's in there, water, oil, or a dry black carboned piston top.
Once you know what you're probably dealing with, you can try the following:
Rust in a cylinder or two? Use a garden hose to blast any crud and standing water out, then use compressed air to clear it out. Once cleared, fill with white vinegar, which will eat the rust. Let sit, and try to turn over the next day or so.
All cylinders look good, and nothing obviously wrong mechanically? Diesel, Marvey Mystery oil, etc all work good. I personally prefer Marvel since I don't have any diesel around. Fill each cylinder, and make sure they're full. Put the plugs back in loosely. Let sit for a day or two, then take the plugs out and see which cylinders still have oil in them and which have let their oil drain. Now you'll know what cylinders are sticking.
Let them sit more, and try to turn the engine over, counter clockwise or clockwise. Patience is a great thing to have. Once you finally get some movement, take time to turn it back and forth to work the oil through and eventually get it turning like it should.
Worst case, take the head off, and beat on the piston with a piece of wood and a small sledge hammer.
Hope this helps. I've had a lot of success with old engines, and I hope I can pass along some of what I've learned.
vince
Naperville, IL