Freeing Frozen Pistons?

modelman · Post by **modelman** » Fri Sep 14, 2018 11:55 am

https://www.dropbox.com/s/pv8lfy8o2dsfl ... r.jpg?dl=0

My pistons where rusted solid in the bores, tried everything, nothing worked so I made two of these, the same thread & length as the plugs, removed the lower crank-case, ( important ), removed the plugs, filled the bores to the brim with grease ( it took a tub-full) fitted the nipple/bolts, & attacked with a grease-gun, it took the long time, & heavy grease gun squeezing, but eventually the pistons began to move & they were pressed out along with the crank assy.
By removing the lower case, there is no stress whatever on the engine cases, they are delicate & easily cracked, for if the bottom-end was seized, all that hydraulic pressure would easily break the case/s. Messy cleaning it after, but the only pressure was on top of the pistons, so all was safe!

Dr. Frankenstein · Post by **Dr. Frankenstein** » Fri Sep 14, 2018 2:31 pm

Interesting tool...it may come to that. I've read about people using a grease gun to do just that, but have never done it myself.

How long did it take to get the pistons to move, and how big was the grease gun? Did you heat the cylinder head too? Did you use two guns, or just go side to side?

What are the dimensions of that bolt?

LOUD MOUSE · Post by **LOUD MOUSE** » Fri Sep 14, 2018 8:46 pm

May I assume you backed the tappet adjusters out so all valves were closed?
You say you filled the bores to the brim (how) then fitted the nipple bolts and then used the grease gun.
??????????????.. ..............lm

modelman wrote:https://www.dropbox.com/s/pv8lfy8o2dsfl ... r.jpg?dl=0

My pistons where rusted solid in the bores, tried everything, nothing worked so I made two of these, the same thread & length as the plugs, removed the lower crank-case, ( important ), removed the plugs, filled the bores to the brim with grease ( it took a tub-full) fitted the nipple/bolts, & attacked with a grease-gun, it took the long time, & heavy grease gun squeezing, but eventually the pistons began to move & they were pressed out along with the crank assy.
By removing the lower case, there is no stress whatever on the engine cases, they are delicate & easily cracked, for if the bottom-end was seized, all that hydraulic pressure would easily break the case/s. Messy cleaning it after, but the only pressure was on top of the pistons, so all was safe!

modelman · Post by **modelman** » Sat Sep 15, 2018 2:11 am

Correct LM.

I forgot to mention the fact that i'd already had the head off, found that both bores were solid rust, tried wood plugs on top of pistons & thumping wilst crank-turning but no-go, any more
'violence' might have caused damage.

Hand filled both with a tub of grease, then as you say, I backed-off the adjusters, so all valves were shut, replaced head & pumped up with a large grease-gun, obviously, this action will ONLY work if the valves are good & well seated.

It 'almost' didn't work as I thought the gun was going to break as I applied so much force, something I noticed, there must have been great pressure in there, for eventually, there was a high pitched 'squeak' followed by a puff of smoke from a piston-skirt !! Then I knew it was moving, & I had to keep going from side-to-side to try & apply an even push from above, it
took a couple of days ( a few thou at a time ) to get them out safely, & thinking about it, I was very lucky since all around the valves was also very rusty, but still remained sealed enough for this process to work.
As for the bolt, I already knew the Dia & thread, but all I did was to visit my local bolt Co. with a spark-plug & said 'a couple of bolts this size please!! ( I'm lucky to have one of the biggest fastener factors in the country nearby) The grease gun is simply a hand-squeeze lever type i've had for 50 yrs!!

brewsky · Post by **brewsky** » Sat Sep 15, 2018 3:48 am

Had used the grease gun method before on rusted brake caliper pistons without any drama, but didn't even think about it for regular pistons!

LOUD MOUSE · Post by **LOUD MOUSE** » Sat Sep 15, 2018 8:17 am

Now ya making since.
How are the pistons and sleeves?
Are they usable? lm

modelman wrote:Correct LM.

I forgot to mention the fact that i'd already had the head off, found that both bores were solid rust, tried wood plugs on top of pistons & thumping wilst crank-turning but no-go, any more
'violence' might have caused damage.

Hand filled both with a tub of grease, then as you say, I backed-off the adjusters, so all valves were shut, replaced head & pumped up with a large grease-gun, obviously, this action will ONLY work if the valves are good & well seated.

It 'almost' didn't work as I thought the gun was going to break as I applied so much force, something I noticed, there must have been great pressure in there, for eventually, there was a high pitched 'squeak' followed by a puff of smoke from a piston-skirt !! Then I knew it was moving, & I had to keep going from side-to-side to try & apply an even push from above, it
took a couple of days ( a few thou at a time ) to get them out safely, & thinking about it, I was very lucky since all around the valves was also very rusty, but still remained sealed enough for this process to work.
As for the bolt, I already knew the Dia & thread, but all I did was to visit my local bolt Co. with a spark-plug & said 'a couple of bolts this size please!! ( I'm lucky to have one of the biggest fastener factors in the country nearby) The grease gun is simply a hand-squeeze lever type i've had for 50 yrs!!

modelman · Post by **modelman** » Sat Sep 15, 2018 3:41 pm

https://www.dropbox.com/s/6shchp9rexoch ... 1.jpg?dl=0

Nah, too far gone, I bought new replacements from your side of the pond!