Stuck pistons on Disston DA211

[Al Smith]

Well if after all the kerosenes ,Kroil,Coca-Cola etc. and it doesn't budge,the Al Smith cure,direct from the frozen cornfields of northern Ohio.
Knock the insulator out of a sparkplug.In it's stead,braze,silver solder,weld,or tap and thread a grease zert.If you welded it,put it aside to cool,while you are looking for your grease gun.If you are like me,this might take a while to figure out where you left it.Pull out the grease tube and fill it full of motor oil.Take the rest of the oil and pour it in one of the cylinders.Now put that plug/grease zert back in[it will be cool by now]
That done,pump away,something will give,you can bet on it.With luck it will free the piston from it's imprisonment of the cylinder.If you are pleased with this,do likewise to the other cylinder.A standard grease gun produces 5 to 10 thousand psi of pressure,enough to move nearly any thing.

 

[Ashley P]

FWIW, Mopar has an aerosol penetrating fluid that comes out as a foam, and appears to have a moly/graphite lube in it. Works well on rusty bolts. And I've heard of soaking siezed auto/farm parts in diesel fuel if you aren't in a big hurry.

 

[Chris J.]

Yesterday I typed in a lengthy response, but the d@mn AS software glitched.
Now for the 3rd time :bang:...

Thanks to all for the advice. Al, you're the 3rd person to recommend pumping the cylinder full of oil. Now, with the saw being a twin cylinder, wouldn't I need to 'pressurize' each cylinder simultaneusly? What if the rings are melted (as in like welded) to the cylinder & piston? I'd prefer not to crack the cylinder(s). I'll try to post some photos tonight. Aw ra best!

 

[Kleek]

Don't pressurize both cylinders, if you do you will find out Mercury rods are not up to the task. Try to figure out which hole is stuck, and pressurize that one. If both, pick on the one that looks the worst. Be careful, you can cause damage to crank, rods, case, etc.

 

[Crofter]

Here's a trick my dad used to use on old tractor engines; even easier on a two-stroke with 1 or 2 cylinders and no valves (hope the piston is inthe top 1/2 of the cylinder). Take an old plug and knock the porcelain out, weld on a 1/8" pipe coupling. Thread in a Zerk, and pump the cylinder full of grease to force the piston to move.

I saw a stuck piston removed in an old Elto outboard (iron piston and cylinder) by soaking the inside with a solution of phosphoric acid (milkstone solvent at the farm store). The phosphoric acid will dissolve the rust fairly fast, but eats iron so slowly that there is no problem.

Tee in a pressure guage so you can see what you are reaching. The grease gun can probably hit 3000 psi or more. 450 psi is as much as I would hit it with and let it sit or tap gently around the outside with the pressure on. Coca cola has been mentioned and I think its acid is mainly phosphoric, but you dont need the sugar, so I like Eyolfs idea. Metal Prep from the automotive paint store is probably a good source too of phosphoric acid. Putting the pressure between piston an head, evenly spread is better than applying it via the crank and bearings. (afterthought) If the jugs are loose, better yet and no worry about working one piston against or together with the other. Make sure the cyl has no air pockets (filled with oil completely) so it doesnt fly when it lets go.

Frank

 

[Chris J.]

More excellent advice, thanks again. For now I'm letting the Kroil do whatever it's doing, or not doing. I sure wish that I lived close to some of you experienced mechtechs; it's always good to have someone to share the blame when something doesn't go right .

Aw ra best !

 

[Bill G]

If the Kroil does not work you will probably be SOL. I hate to admit it but the stuff works. It seesm to have the ability to do what it is advertised to do---penetrate.

Bill

 

[Lawn Masters]

I'd probably be unbolting everything and going at it the old fashioned way by this point. the way I figure it, if you unbolt the cylinder, it may come apart and you might be able to get it workin from there.

 

[cbfarmall]

I'd probably be unbolting everything and going at it the old fashioned way by this point. the way I figure it, if you unbolt the cylinder, it may come apart and you might be able to get it workin from there.

He does have the cylinders loose. And I'm sure he does have it stripped down.

Chris B.

 

[Chris J.]

The DA211 is a different from your normal chainsaw (yes, I'm aware that most of you know that). The cylinder bolts are built? into the saw, and come up through the bolts holes in the base of the cylinder. I've removed the nuts, and managed to pry the cylinders loose so that there is some play. The bolts coming up through the cylinder base limits the amount of play, as does the fact the cylinders sit very close to each other. Also the carb doesn't feed the gas directly into the side of the cylinders, it feeds in indirectly from the bottom.

I don't have the mechtech vocabulary to properly describe the saw, and a picture is worth a thousand words. I'll get photos tomorrow, and maybe post the IPL. Hopefully the Kroil is slowly, but surely, working.

I do appreciate the interest and advice. AS has the best chainsaw forum! And to my cyber friends over at you-know-where I want you to know that I don't mean that as a slam .