Getting a stuck engine loose
A trick that I learned about 40 years ago. First - Back off all the rockers
from the valves so the valves are closed either by the adjusting screws or
removing the rocker arm assembly.
Prepare spark plugs by removing the ceramic core, threading the center and
installing an air line fitting into the spark plug. You can do one or enough
for multiple cylinders. You may want to prepare several versions. One with just
the air line fitting and another with a tube that extends about an inch into
the cylinder beyond the top of the engine block. This is for the cylinders
where the pistons are about half-way up the cylinder.
Pour a very light solvent into the cylinder. Do not use Coke, WD 40 or any
other residue leaving material into the cylinder. (Coke WILL make it worse). I
often used kerosene or an engine flush. Screw the air line fitting into the
cylinder and apply air pressure through a regulator starting with about 25 lbs
of pressure. Gradually raise the pressure to about 75 lbs. If there is no, or
little air leakage, past the valves leave the pressure on for several hours. If
there is air leakage past the valves, release the pressure and fully fill the
cylinder with the solvent to the top of the air fitting. Use the plug with the
tube that extends about an inch into the cylinder beyond the top of the engine
block so the air enters into the liquid. This will put the liquid level above
the valves helping to seal them. You are trying to force the solvent past the
slots in the rings and around the rings so it can work on the debris on the
piston walls.
Be patient, I often had to do this over a period of several weeks or a month.
If you donbt mind spoiling the paint on the engine, applying a little heat
with a butane or propane torch helps a lot. You can easily suck the solvent
back out of the cylinders with a turkey baster and rubber tube. Turn the engine
over with a socket on the front pulley, or by a lever through the starter
opening on the teeth on the ring gear. Never try with the starter. I have done
this successfully on a number of engines.
If this does not work, you will likely have to tear the engine down but first
you may want to install a grease fitting into a spark plug, but solvent into
the cylinder, and use the grease gun to FORCE the solvent past the piston. Also
apply heat at the same time. Be careful with this as I have seen cracked
cylinders if pressure is taken to excess.
When trying to remove stuck pistons after the head is off, NEVER pound on the
tops of the pistons even with a block of wood or a steel plate on the piston.
There is a good chance of cracking the cylinder wall. Some time the crack is
not visible and only shows up down the road or during magnetic particle
inspection. I have found the best method is to make a steel plate with a large
tapped hole in the center and holes for the head bolts. Drill a hole in the
plate so you can squirt solvent into the cylinder. Place a round steel plate on
the top of the piston. Bolt the plate down onto the block. And with a
b pusherb bolt threaded through the plate push the piston down. (Works like a
gear puller). Apply plenty of solvent and heat. If you are patient and gentile
it works great.
John b Wisconsin
54 Nash Healey Coupe
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