Freeing a stuck engine

Before you get out the sledge hammer and a block of wood and start pounding, there are a few things to consider. Most importantly:

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{{Note1}}Using a breaker bar to turn a frozen engine over by the crankshaft bolt is not recommended. The acceptable method involves turning the engine from the flexplate/flywheel, or by using a crankshaft socket that fits over the snout of the crank or bolts to the damper. Exceeding the torque rating of the crank bolt can- and will- snap it off, costing a lot of time and trouble to fix.

After allowing the penetrant to settle in for a few minutes to overnight, try to turn the crank in the reverse direction of rotation (CCW as you fac the engine looking towards the distributor) to remove the tension on the rings. The penetrant between the ring and the wall will eventually break the ring free from the cylinder wall. It may take a dozen or so tries before all of the stuck rings and bearings are free but with each successive try more fluid will fill the voids until the engine is free to turn. Allow the engine to make two or three revolutions before stopping the exercise. This will allow the excess penetration oil to evacuate itself from the combustion chambers and for some of the oil in the crankcase to move in the system. The engine will now have a new place to rest while the lubrication seeps into the surfaces of the internals.

Many years ago the writer bought a Commer van with a stuck engine. The poor aftermarket ignition wiring (the van originally had a diesel engine) had caused the engine to quit. The vehicle had been idle for over a year judging by its tax disc so Plus Gas was introduced into the plug holes daily for over a week. Trying to force the starting handle stripped the thread on the aluminium alloy jaw nut so that method of attack had failed. Fortunately the defective alloy part had been discontinued and replaced with a steel part so the new part was bought and fitted. Unfortunately even when the starting handle had timbers clamped on it for extra leverage the engine could still not be turned!  At this point the starter motor was tried but the battery was too weak. A new heavy duty battery was purchased and this succeeded in freeing the engine on the third impact (the current draw was so high that the earth braid smoked!) The engine then fired-up and ran OK and at this point the astonished seller rushed out and said "Are you an electrician or something?" It was a great van and basically all it needed was two weeks of soaking with releasing fluid, a new battery and some attention to the ignition circuit. Engines from boats which have sunk are much more difficult.

Start by turning the crank, even a small amount will- over time and with repetition- cause it to break loose. Or iy'll tell you that the engine is well and truly frozen up and needs to be disassembled for a proper rebuild. Even a degree of movement or a thousandths of an inch is a start in moving the engine's reciprocating assembly. Allow time for the penetrant to work and don't get impatient.

We know that steel or iron will rust. Aluminum will form a white powdery residue (aluminum oxide, or aluminum 'rust) and may form a dark grey to almost black coating caused by the oxidation of the metal. Brass and copper will be covered with a green corrosion. Each condition will use a different approach in most cases.

*Remove non-essential accessories that aren't required to make the engine rotate. That means that you can loosen the belts off or remove the alternator, water pump, intake and exhaust manifolds, distributor, heads, oil pan, etc. Get it down to where you can have a good look around and see where the problem area lies.

*Keep the engine in a secure holding device. If it's the frame of the car or truck, that's good. If the engine is loose, find a way to hold it down. Remember, the tensile strength of steel is greater than wood. And if one bolt is good, a half a dozen would be better. If using an engine stand, use caution that it doesn't tip. Alight-duty three wheeled engine stand won't do it a long breaker bar is going to be used to turn the crank.

*Using an oak block and a dead blow hammer of your choice, SHOCK each piston with a few blows. A air chisel with a flat bit and an oak block like the mushroom end of an axe handle works good, remember you are just trying to loosen the rings NOT move the piston, just let the bit vibrate the oak block and piston. When the rings break free you will see your lube run past them into the block. Any piston which is at TDC or BDC will not give you any mechanical advantage in rotating the assembly by hitting it. The initial strike is to just loosen the rings in the piston lands and break the rings free from the walls of the cylinder. Pistons that are in between TDC and BDC will provide the best opportunity to move within the bore.  

*There are two places in which you can apply rotational force. One is the crank pulley and the other is the flywheel. Use whichever is accessible the easiest. Do not use pulleys or the outside ring of balancers to turn over the engine if at all possible. Don't use the balancer bolt, either. Damper/balancers can be damaged and the damper bolt will strip if excessive torque is applied. Instead, the safest/easiest way to turn the crank is to use a tool that allows a large ratchet or breaker bar to be used, like the crank turning devices shown below. Both sockets that use the crank key, and adapters that bolt to the inner hub of the damper are made for turning the crank. Crank keys and keyways can shear with abnormal force. Be sure of the bolt grades before applying force. Remember to try to rock the crank CW and CCW.