Seized engine disassembly

[rcamacho]

The engine on my M37 is seized up. I've removed the head and have all cylinders soaking in a puddle of diesel fuel. The boar look good on all six and the spark plug condition indicated the engine was running fairly well before it was stored. Any suggestions on how to go about getting the pistons to move? I've looked at the burning/heat techniques in addition running a soft 3-3.2" OD pipe to tap lightly on the pistons.

[isaac_alaska]

If it were mine I'd use a block of wood about the diameter of the piston and another block of wood as a hammer, and knock each piston. Shouldn't have to wail on them very hard at all. Have you tried a big breakerbbar on the nut at the front of the engine? Sometimes that works, sometimes it just tightens the nut down farther.

[Tom P]

Diesel is ok but I would try a better penetrant for a few days before I hit anything.
Thinking ,PB blaster, Etc. Kroil oil is what I like.
Or 50/50 mix of cheap ATF and Acetone. works very well.

Be sure to put some on/around the valve stem/guides.
They stick easier than pistons do.

Good Luck
TGP

[rcamacho]

I neglected to mention that there is already PB blaster in the mix before adding diesel.
I've used a large breaker bar on the front crankshaft nut and it's solid, no movement.

[isaac_alaska]

If it's a siezed valve or lifter you would expect a bit of movement at the crankshaft, if you rock the breaker bar back and forth. there's usually a little slack on the cam chain.

[w30bob]

rcamacho,

I wouldn't be hitting the pistons with anything metallic!...............they're cast aluminum and will crack pretty easily. I'd use something wooden and as close to the bore size as possible to distribute the load evenly across the piston surface. Is the engine on a stand? I know some will disagree, but if it were my engine I'd pull the crank before I whacked anything. Think about it a bit. If all the pistons are stuck.......whacking one and expecting the other 5 to move is a pretty tall order. It puts all the stress involved with freeing all 6 pistons on the one piston you're whacking. If you pull the crank you can whack each piston and the only force each piston has to overcome is that which is freezing the rings. By pulling the crank you can also make sure the crank bearings are in good shape.....even if it's only for piece of mind. And if the pistons are stuck that tight you're going to need to pull each one and replace the rings anyway..........so save yourself the headache and maybe a cracked piston or two. By the way............if you whack any pistons that are at TDC or BDC you're not going to get the crank to move....only crack those pistons. You can tell if any are at BDC by measuring how far they are down the hole, and TDC is obvious. With the crank out you can whack them all.

In terms of penetrating oil...........the best is a combination of ATF and Acetone. 50/50 is recommended, but more Acetone won't hurt anything and might help. Acetone thins the mixture and has a low surface tension, so it gets into every crack and crevice. When mixed with ATF it drags the ATF with it into those tiny cracks and crevices.......then evaporates leaving the ATF to lubricate. So I'd put a healthy amount of ATF/Acetone on each piston top and let it sit overnight. Then with the crank out I'd lightly tap each of the piston tops with a piece of wood. Keep tapping each piston without going crazy and things will start to loosen up, unless you've seized a piston and don't just have frozen rings. Just make sure to wrap each connecting rod in a rag so as not to score anything when they start moving down the bore. Then you're going to want to pop each one out, get those ring grooves clean, and replace those rings. Doing this one piston at a time prevents you from mixing them up when re-assembling.

If pulling the crank is really too much trouble then at least have someone put some torque on the flywheel or the crank bolt while you're tapping each piston. Don't go nuts on the crank bolt or you'll have another problem to fix. Breaker bar works, as does someone standing on the hand crank starter rod...........if you know what I mean.

regards,
bob

[RMS]

if a few days of soaking has failed to free up the pistons it is time to call them junk. pistons are cheep and no compromises should be made that will cost you more later. pull the power plant,...,..bla...,..bla..,..bla.,..., mark and remove bearing caps,install bits of rubber hose on rod bolts to protect the bolt, crank and the bore, pull crank . with the block resting on soft wood use a large wood or brass drift on the piston pin to drive the pistons out of the top of the block as they will not clear the bearings if hammered down. now if you don't care and just want it to spin at no cost, you can try a big bar on a flywheel tooth and pry against the bell housing. you may wreck a tooth but its better than twisting the bolt off in the end of the crank or doing unknown damage to the entire rotating assembly by hammering on the pistons to get the crank to spin.

[rcamacho]

#5 let loose today soaking in diesel, it's dry as a bone so at least that cylinder is good to go.
Thanks for the advice, yep I'll very carefully tap on the cylinders to see if I can get he rings to pass solution. Then it's out and complete inspection/rebuild.
Now to clear space in the garage...

[rcamacho]

#2 is passing diesel past the rings now. Making slow progress