OT stuck rings on piston - removal tips?

I am working on a 1959 Mercury mark 55a - one piston was stuck badly and almost gave up on in until my neighbor was able to get it out - the rings are stuck in the grooves and will not budge - any tips on how to get these out? It is a two stroke motor. I am even wondering if this piston is going to be reusable anyway? I am going to put new rings in throughout.

Soak em in ATF or try heating them with a torch

Actually, you can use an appropriately sized pin punch to tap on the end of each ring at the gap and even if it doesn't loosen the whole ring you will be able to get them out a piece at a time. Have often used this technique to remove badly stuck rings in diesel engines. Always works but is sometimes messy.

I used to buy this by the litre to use as a bath for corroded stuff or for freeing stuck pistons etc. I once found a thick brass belt buckle under a 50's chev truck seat and it was thick with green corrosion. the next morning, after a bath in this stuff it literally looked like it had been glass bead cleaned.

First it was called: "Chrysler exhaust Heat Control Valve Penetrating Fluid" WHEW! It goes under a different & shorter name now -- Mopar, I think. toxic stuff and it is NOT an oil per se, so it needs to be cleaned and followed by a chaser of oil afterwards.


http://www.ebay.com/itm/old-Chrysler-MOPAR-Valve-Solvent-Penetrating-Fluid-Oil-Can-8-oz-Tin-Can-only-/261546525888?pt=LH_DefaultDomain_0&hash=item3ce56344c0

• 50/50 acetone and ATF
• Power Lube by CRC

and my favorite:
Amsoil MP

What are your thoughts on the possibility of re-using that piston? They are hard to come by and very expensive - even having a problem getting set of rings for it.

Lee

If you can get the rings out without damaging the lands they should be fine.
Are the pins nice and snug?

yes, there is some side to side play on the bearings which are those pin type but little or no movement elsewhere - I think once the crank is in place and new bearings/seals installed it will be pretty solid - it was used only on lakes and although old I really don't think there are many hours on the motor.
Lee

When I worked as a line mechanic at a Dodge dealership we used a similar spray called heat-riser solvent spray. A lot of mechanics used that spray, carb cleaner and electric contact cleaner as their only aerosol sprays. That was some good stuff. It sprayed gray.

Found this in a pdf:

"My preferred solvent is a Dodge product called "heat riser solvent" (I just replenished my stock and its now called "Rust Penetrant".) Same product, same part #), about $6.00 comes in a 10 oz. spray can. Part # 4318 039 AB."

I remember buying a can of Autopar "Rust Penetrant". It was a black can and was the same stuff as in that old can photo I posted. I had often wondered why they hadn't simplified the name, because Joe public didn't know what a heat control valve was, so the stuff sat on the shelf at chrysler dealerships for longer than it should have.

but I still way prefer Amsoil MP because it cuts gum and rust instantly and leaves a beautiful and STABLE oil film after the fact. Nothing like it, I swear.

I couldn't resist . . .
Here's a photo of my disk-to-rim bolts. Rivers of rich brown rust already poured off them but i haven't touched them in a month. This is why Amsoil MP is also known as a "metal protector". Notice the chocolate brown rust still laying on the 3rd one from the right and the brown puddle under the far right one. Normally they would now look just dry oiled and blackish but I sprayed so much that the wet carrier hasn't all evaporated yet.

I used that technique on 2 stroke snowmobile engines and if you are careful enough the rings will come off in pieces and the piston will not be harmed

Get yourself a cheap air impact chisel set. Cut
one of the tools off to leave a flat end.

Get yourself a hard oak board 1" X 1" and wet the
rings with some penetrating oil or diesel fuel and
set the board on the end of one ring and then
start hammering on the other side of the board
with the impact tool. I've never failed to free up
rings doing this. Don't attempt to remove a ring
till it is free all the way around.

I also have a tool I made about 40 years ago to
free up stuck pistons using the same impact tool.

I cut out a flat piece of steel about 1/2" thick
that will sit in the bort on top of the piston and
then weled a big nut in the middle of the plate so
the tool won't move around and after soaking just
start hammering on the top of the piston. "Always
works!"

Zane

they went in, they'll come out.
Just like freeing the engine, patience is key.
soak em, and work with your pick, little piece at a time.
When you break a piece out, more solvent. Once the solvent gets under it, it will go faster.

From your picture, I'd re-use that piston without a second thought. Which makes patience even more important, so you don't harm the ring grooves.
The first break, you can use the other ring end as the fulcrum.
After that use something as a fulcrum when prying, so you don't mar the piston up.

Warm it with a torch & let it cool again. Keep doing this until the rings come loose. Use a good penetrating oil as they cool. You should be able to get those off without breaking them.