I have offered to rebuid a half engine for a mate. Problem is that the pistoins are stuck in the bore. I have diesel sitting in all bores at present and two have finally leaked past the rings. Is there anything else I can use to free up the carbon in the ring grooves so I can have a go at turning the engine over or shall I just leave the diesel in and hope it works?

I have in the past ,removed the crank then used a lump of wood and a BFH to get pistons moving enough to then use a cylinder hone above the pistons before trying to remove

Can you turn it over and let it soak from the bottom as well? Then crank out and knock them down with a piece of 2x2 and a big hammer from the top.

Is the engine still in the car ? as if so, crank it on the starter, i did this on a seized Merc 200, and it ran for many more years

But as said, remove the crankshaft and carefully with a piece of soft wood, and mallet try from sump side, and spark plug side to get the piston to move, the piston will probably go down more, some engines, the piston will go out the bottom,

The pistons, will probably be alright but the rings will be goosed

steve

At present I cannot get the crank pulley bolt off so taking the sump off is an issue. At present I just want to get it tunring over. The engoine isnt in the car and it has been sat for years. The bores look just about OK but who can tell what its like where the rings are sitting.

Leave the diesel for a bit longer or remove it and coat the bores liberally with Plusgas?

Plusgas has got me out of jail an many occasions