Basic data: Inspecting, Maintaining, and Replacing Piston Rings and Pistons
 

Basic data: Inspecting, Maintaining, and Replacing Piston Rings and Pistons
http://www.tpub.com/content/engine/14076/css/14076_66.htm

How to free stuck piston rings? Make piston stew!!
 

How to free stuck piston rings? Make piston stew!!
http://www.honda-tech.com/showthread.php?t=2001666

Never soak a piston rod assembly in varsol. A friend of mine did with a 1948 buick engines parts. The wrist pins were loose before the soak. The rod was so solidly seized up after the soak even on a proper press and piston jig the pistons were a little distorted getting the wrist pins out.

I just thought I would mention it rather than anyone ever considering using varsol as a soak.

On the pot cooking to release stuck rings the time out of the pot may be important. I believe the rings are being loosened because of the diferential expansion rates of the aluminium and cast iron or steel rings. The more cycles accomplished with the greatest coolling spread the better. Should result in fewer boiling cycles as well.

Around here in our climate rings stick far worse on gas engines sitting than diesels. I believe the tighter clearances of piston to wall fit in manufacture on diesels tends to retain any oil longer. Or the atmospheric moisture cannot penatrate as easily. More surface tension is present on any oil remaining in the area as well perhaps.

Therfore an older well worn engine will stick easier than a tight one. Just because the clearances are greater.

Does anyone know if the rate of sticking is higher for compression rings than oil rings.. surely they do not all stick at the same moment in time...

Can the sticking of one type affect the rest of the rings sticking ?

Any guess as to what would make Varsol ... a pretty standard solvent.. cause that rod end problem ?

I never researched to find the why with the varsol. It was the only possibility in his case though.

I did at the time hear an automotive machine shop verify it was the cause of the problem. It is a very common solvent used in many parts washers I think. .

What rings stick first may be more dependant on the actual material used in manufactuing them. Some are cast iron or used to be and some are perhaps cast steel. Perhaps when a set is purchased their composition is different.

Also what end of the piston sees the most atmospheric moisture. May be a factor. I consider it almost total death to store an engine long term in a damp location unless really protected. If those aluminium pistons become oxidized it would be like putting a grinding compound in the engine. Aluminium oxide is very hard.

I too hope some chemist type might enlighten us about what varsol is actually composed of that could account for this problem. I really do not have a clue why it does this myself.