Unsticking a Stuck Engine

Edited by Tim W. Elder

The following are “stuck engine” ideas collected over the years from various people and publications. The people whose ideas are represented below include:Lon Cook, Ted Elder, John Evans,Mike Healy, Loren Lindsay, Ronald Peck, Roger Peterson, Joe Pinchbeck, Scott Roberts, and Joe Williams. The publications include: ALF Yahoo Group, Seagrave Yahoo Group, Antique Power, Old Cars, and Skinned Knuckles.

This addresses an engine that is stuck from sitting, not from some mechanical failure, overheating, or lack of lubrication. Unsticking an engine takes a great deal of patience and luck.The engine didn’t seize overnight, so don’t expect immediate results.

Loosen the oil drain plug, but don’t take it out. Loosen it more by hand to see what dribbles out first. If water, how did it get there? If down through the cylinders or valves, you probably have rust issues. Can you inspect any portion of the cylinder walls; perhaps through sparkplug or valve port cap holes?

Realize that you are taking a risk if you use the steps below to get the engine free and running: --Have you done any internal damage that will come back to bite you? --Will a piston ring broken during the unsticking efforts now score the cylinder walls? --Will a broken piston ring land cause future expensive problems? --Did rust on the cylinder walls scuff the pistons, rings, or cylinder walls? --Did debris get into the bearings? --And more.

Do not try to free the engine by towing with another vehicle. This might lead to issues that you really don’t want—such as a broken differential.

Be sure to observe everything! For instance, if the engine wiggles back-and-forthonly slightly, but won’t turn any appreciable distance, perhaps an accessory is stuck and the wiggle is the gap between gear teeth. Are the generator, water pump, and distributor all able to move? And the very obvious—is the transmission in neutral?

In general the techniques below are in order of escalating force. I assume you have already tried the starter or pulled on the crank handle with no sign of rotation of the engine. No matter which of the techniques below you use, once the engine turns a little bit, you probably have it made. Work it forward and backward many times, hopefully turning just a bit farther each time, until it will turn all the way around. How do you turn the engine backwards with the handcrank or starter? You don’t; keep reading for how.

If you can access nuts on the crankshaft on the front of the engine and on the clutch, get sockets that fit, a breaker bar, and probably a cheater pipe. Try to turn the engine from both front and back; both because the front will turn it in the normal direction and the back/clutch will turn it backward. You need to try both directions in case a valve, and not the pistons, is stuck.

At the outset you don’t know whether pistons or valves (or both) are stuck. See how you can access the ring gear teeth on the flywheel; you might have to pull the starter. Then, using a large pry bar, try turning the engine backwards. You can also put it in gear and turn the drive shaft by hand, bar, or strap wrench—a drive wheel may have to be jacked up. Stuck pistons won’t move, but stuck valves will let the engine turn a short distance. If it will turn backwards a short distance, and forward not farther than it was before, you have a valve, or more, sticking. Your task is to free them before addressing the engine again. This may mean you will want to “unadjust” the valves so they are out of the picture for now—but they do have to be dealt with later.

The engine may be stuck from the varnish left after gasoline evaporates. One article suggested that you fill the cylinders with fuel oil mixed with acetone if you think gasoline varnish may be the cause of the stuck engine. (Aside: acetone is one of the few solvents I have found that will work on gasoline gum.) Then fill the cooling system with very hot water (if the radiator is off, plug the bottom outlet, of course.) After a day, drain the formerly-hot water and repeat this,and tryturning the engineagain while the water is hot. In several of the techniques below, hot water in the cooling system will increase your chances of success a bit, because the slight expansion of the block will help the penetrant do its job.

To prepare for the assault below, you should remove the sparkplugs and fill the cylinders with some sort of penetrant—perhaps you will want to use kerosene or ATF for this since they are not expensive and have some lubricity. (I am not specifying the penetrant beyond this, because everyone has a favorite that works best for them.) Allow this to soak for a couple of days or more. Also expose the valve stems so they can be lubricated. When the engine is finally free to turn, remember that this penetrant will come squirting out of the sparkplug holes, plus get into both manifolds through the valves! This operation is definitely not a clean one; you probably will want to cover the floor under the engine and wear some pretty old clothes.

If the cylinder walls are very rusty, you should remove the head in order to clean them up so the piston and rings do not have to grind through the rust and other crud. First scrape away the loose stuff—a vacuum will get it out of the cylinder. Then use a wire wheel on a drill motor to get more rust off. (A knotted wire wheel is more potent, and a flexible shaft machine will be a great help.) After this a cylinder hone will clean up the cylinder wall, perhaps all the way down to the piston. Do the same below the piston if you have access past the rods and crank after removing the oil pan.

When the head is off, if this is a sleeved engine, you will have to anchor the sleeves if you don’t want to risk them coming out.

In many of the cases below, you will have to apply a force. After you do, go away for hours or days, returning several times to make sure the force is still applied and to see if anything has moved.(Don’t forget that hot water in the cooling passages may help.)

This method may be quite messy! And the head must be on. Make sure all the valves in that cylinder are closed (unadjust the tappets if you haven’t already.) You have already filled all the cylinders with a penetrant; make sure they are still full. Knock the porcelain out of a sparkplug, and weld in a grease fitting; add a pipe nipple if that makes it easier to reach. Now use a grease gun to pressurize the cylinder; one halfway down is best. Check every day or so to make sure it is still pressurized. If you decide to pressurize more than one cylinder at the same time, make sure they will all turn the engine the same direction.

If the above steps have freed the engine, you must drain the old oil and refill the crankcase with new oil before trying to start it. Change the oil again after it has run a couple of hours; be sure to drain when hot so that more debris is carried out.

The following are quite a bit more work, so let the engine soak in the penetrant a couple more days, then try again before trying the techniques below.

This utilizes a jack in an attempt to turn the engine. Do not put the jack under the crank handle, because it is probably not strong enough. Remove the oil pan if you haven’t; you should have removed the sparkplugs already. Of course all cylinders should have been soaking in penetrant for at least several days. With the oil pan off, you may want to loosen the rod bearing caps, and check each piston to see which one (or all of them) is stuck. Pick a crankshaft throw that is part way up, halfway up if possible; and position a jack under it with suitable blocking so that the force of the jack will try to turn the engine—either direction is OK. Either a mechanical or hydraulic jack should do the job. If the engine doesn’t turn, leave the jack force applied and go do something else for a day or so. Then recheck the jack.

This requires that the head be removed (this is not available for tee-head engines.) You will need several things:--Arectangular steel plate, 5/16” or more thick and large enough to thread 4 bolts into headbolt holes (or fit over 4 studs;) in addition to these 4 bolt holes, this plate needs to have a larger hole centered over the cylinder. –A sturdy and thick wood block, turned round a bit smaller than the cylinder. End grain should face the piston; shape it if the piston is crowned. –Another steel plate, perhaps ½” thick, to fit in the cylinder on top of the wood block. –A hardened (Grade 5 or 8) fine thread bolt and nut, 9/16” or more in diameter and about 6” long. You may have to tack weld the nut under the center hole of the rectangular plate. If you want to push more than one piston at the same time, you need one set of the above for each. Put the wood block and the steel disc on the piston, put the bolt through the center hole in the rectangular plate and thread the nut on, then bolt the rectangular plate to the block with the nut toward the piston. Now turn the bolt to put considerable pressure on the piston; an occasional hard rap with a hammer on top of the bolt may help.

The above technique tries to move pistons down; the jack under a crankshaft throw (also above) tries to move pistons up. Perhaps you will want to try both together, but coordinate your efforts so you are trying to turn the crankshaft in the same direction.

The above techniques attempt to turn the engine as a whole, but this means all the pistons have to move. If you have not had success so far, it is time to remove the crankshaft and head (if you haven’t already) so that force can be applied to one piston at a time.

And last: Remove the engine block and place it upside down on the floor. Make a platform, maybe from angle iron in an “X” pattern, so a jack can sit on the block; there must be space for a chain to enter the cylinder on each side of the jack; the connecting rod will be sticking through too. Thread a strong chain around the piston wrist pin and over the jack, which is on the platform of course. Work the jack to apply force to the piston through the chain. You may not have enough room for this unless you are dealing with a large engine.

“I-Give-Up” last: Take the block and stuck pistons to a machine shop that has a hydraulic press.