Freeing Frozen Pistons?

Dr. Frankenstein · Post by **Dr. Frankenstein** » Sun Sep 09, 2018 9:37 am

This was orginally posted under 'Rocker Arm Pin Removal', since I was trying to get the engine apart to see why the engine on my CA77E won't turn, and LM wanted me to keep him apprised of where I am in the process, so here I am. I'm putting up a new post because I've wandered into a whole different topic, that of getting the frozen pistons out of the cylinders.

The bike has sat for an unknown number of years. I bought it essentially just for the gas tank, but the inside of this engine (except for the stuck pistons) is beautiful, so I've decide to see what I can do to make it run again. It LOOKS like the PO ran it out of oil, causing the failure - there was not a lot of oil that came out when I opened it up, and what Did come out was blacker than midnight in a coal mine, and smelled burnt.

Currently, I have the engine totally apart except for the upper engine half/cylinders. The crankshaft is still attached through the upper case to the pistons, which are stuck in the cylinders at TDC.

I have tried soaking them with PB Blaster, pounding on the piston crowns with a drift and a hammer, heating the cylinders/pistons with a heat gun (but not a torch, yet) and tried pressing them out - or at least trying to get them to move - with my 12-ton shop press, all to no avail - maybe I'm just not trying hard enough...?

I have also tried various combinations of the above, but still no luck getting them to move At All.

After much research online, I plan to flip the engine over and fill up the cylinders with a 50/50 combination of ATF and gasoline or kerosene and let them soak for a good while.

Or throw in the ATF and gasoline and light it on fire and see if That has any effect, hoping that it will expand the pistons enought to get the fluid down around the rings. But there is absolutely No space around the piston edges on the face of the cylinder head itself. It is TIGHT.

But my question is, what else can I do/try?

rustywrench · Post by **rustywrench** » Sun Sep 09, 2018 10:23 pm

The rust scale in those cylinders can be so strong I have literally pressed the sleeves out of the block. That meant that I snapped the flange off to get them to move. I did not like that resort but I had to get more stubborn than the rust. My next lesser resolve is to drill a series of 1/4 in holes around the piston top to relieve the pressure. I have even used a saws-all through the side of the piston to relieve the pressure. Both have worked well though you will no doubt need to replace the sleeves. But then if the rust is that tight, the odds of saving the sleeves is pretty remote at that.Good luck. Rusty

brewsky · Post by **brewsky** » Mon Sep 10, 2018 7:03 am

I used a 2x4 bolted to the cylinder of a T500, some all thread, and mix of 50/50 acetone/atf to free up a rusted/seized piston.

Tightened it each day as much as I dared and let it sit overnight, till it finally popped loose out the bottom with minimal damage. It took several days

https://www.flickr.com/photos/143996376 ... ed-public/

https://www.flickr.com/photos/143996376 ... ed-public/

Dr. Frankenstein · Post by **Dr. Frankenstein** » Mon Sep 10, 2018 7:18 am

Now there's an idea - I do have a crankcase puller I could attach to the cylinder head with the two side screws...apply some constant pressure and heat try to push them down in the cylinders a bit, just to get things started to loosen up...I'll let them soak for a while before I see if I can get them to move. I thought about seeing what effect my can of carburetor parts cleaner has, if any, if the current brew of ATF, acetone and gasoline doesn't work.

Brewsky did you ever get that bike running?

jkv357 · Post by **jkv357** » Mon Sep 10, 2018 8:22 am

I would try heating the cylinder with a torch.

It's amazing what heat will do. It's the temperature differential between the parts that does the work.

I had a seized bolt on a part that I though may have red locktite on it, so I popped it in the oven at 400 to see if it would free up. No luck. Chewed-up the opening on the socket head (Allen) bolt trying to get it to budge.

Then I heated the area around the bolt to about 250, and you could just about spin it out with your fingers.

Might be a bit different dealing with corrosion, but I think it would be worth a try.

brewsky · Post by **brewsky** » Mon Sep 10, 2018 9:10 am

Dr. Frankenstein wrote:Now there's an idea - I do have a crankcase puller I could attach to the cylinder head with the two side screws...apply some constant pressure and heat try to push them down in the cylinders a bit, just to get things started to loosen up...I'll let them soak for a while before I see if I can get them to move. I thought about seeing what effect my can of carburetor parts cleaner has, if any, if the current brew of ATF, acetone and gasoline doesn't work.

Brewsky did you ever get that bike running?

No, it's been on the back burner, but I'm getting ready to pull it off any time now.

It took a month soaking and working on the pistons to get the rings out without damage.

Turned out much of the rust was from the rings themselves.....going to try to re-use the pistons with new rings and a hone job

Dr. Frankenstein · Post by **Dr. Frankenstein** » Fri Sep 14, 2018 6:42 am

So far I have had no luck with ATF/Acetone, so I changed it out for carburetor cleaner, the stuff you get in the can at the parts store; I'll see if that helps.

But has anybody tried mixing up a stiff mix of naval jelly and water and filling up the pistons with that? Might work - it is rust after all that's keeping the pistons in there...it works well with gas tanks.