The absolute worst thing you can do is try to make the engine turn by towing the truck! If it's stuck really tight, you can bend connecting rods, trash gears in the transmission, or break a rear axle shaft.

Pull the spark plugs, and squirt some type of penetrating oil into the cylinders. Some people swear by PB Blaster, Diesel fuel, automatic transmission fluid, and even WD-40. Personally, I like Kroil.

www.kanolabs.com

I've used it for 30+ years, and it frees up stuck engines the other stuff can't touch. 2 or 3 ounces of Kroil in each cylinder will creep past rusted-tight piston rings and go into the crankcase in about a week's time, where you can drain it out and pour it through again. Drain as much oil as possible out of the crankcase first, obviously. After a few cycles like that, put a pry bar on the flywheel teeth and nudge the crankshaft a few degrees in each direction. When things tighten up one way, turn it back the other direction. Also remove the valve cover and soak the tops of the valve guides to try to free up any sticky valves. Once you get the engine making full turns in both directions, try spinning it with the starter and do a compression test.

Worst-case scenario will be deeply pitted cylinders that will need to be rebored or sleeved. You just might get by with a good cleanup, and/or maybe a valve job. Just don't get impatient and destroy an otherwise good engine by trying to force things.
Jerry

Last edited by Hotrod Lincoln; 04/03/2011 12:28 AM.
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