Posted by vince on Monday, August 11, 2003 at 6:44PM :
In Reply to: Freeing up stuck flatheads, help needed! posted by Eric B. on Monday, August 11, 2003 at 12:21PM :
Hi Eric,
I'll try not to retell what some others have said...
I've had a lot of luck freeing up stuck motorcycle engines, even some that have been left out in the weather for years. Often it's too much of a hassle to remove the engine to work on it, or too costly for new gaskets, etc.
First I like to get an idea of what's in the cylinders. I tape a Q-Tip to a long rod and use that to see what's on the piston, carbon or rust. If rust, if the rust is damp it seems easy to break it loose. This also tells you where the cylinder is, TDC or otherwise.
I've had lots of luck with Marvel Mystery Oil, but sometimes it takes time, like in months. If a cylinder is stuck, the oil won't drain into the crankcase.
I've also used mild acid on rusty cylinders like vinegar, let sit for a day or two, then blast it out with a water hose, then air dry with compresssed air, then fill with oil. The acid helps to eat away some of the corrosion so the oil can work.
To loosen an engine, I've had best success using the crank pulley nut/bolt, but be careful not to crank on it too much. Sometimes going one way, then the other helps, too. I'd imagine towing or shocking with the wheels would also work, but might be hard on some driveline parts.
If, after a few months of waiting, no luck, it's time to go into the engine. I like pulling the head, as it allows me to see just what is going on in there. The old hammer with a block of wood works, but try it on all cylinders and not just the stuck one, as the different shocks will help to break loose the engine.
Sometimes over time, a head gasket will develop a leak allowing coolant to enter the cylinder and rust to begin.
Seafoam (from NAPA, etc).....that's been very useful as a fuel system cleaner and stabilizer, does a great job with carb float bowls full of cruddy old fuel. Turns the hardened fuel to a soft, easy to remove mush.
Hope this helps,
vince