How to break loose piston?

[schlik83]

I have a 787 seadoo engine and it is siezed up... there was some rust on the cyl wall when i took the head off,, i soaked it for a couple days in transmission fluid,

then i took that fluid off the cyl and sprayed it down with pb blaster. let it sit a couple hours, tried hitting it with a sledge hammer and a piece of wood... still wouldnt budge. I cant move the pto, I took off the pump completly and I cant move the driveshaft either.

What Im gonna say next will probably get me cursed at but here goes... I figured that im gonna have to do at least a top end rebuild so that means the pistons are trash either way, and i really want these rings to break free... so I took the sledge hammer directly to the piston with several hard wacks... wouldnt move. :ack: Then i took out my air hammer and cranked the psi all the way to 150 and hit on the top of the cyl with it for a few seconds at a time and it wouldnt move with that either... :ack::ack: All of this has carved up the top of the cylinder a little but I did not damage the cylinder walls at all.

My question is what is going on? And how can I get these pistons loose? Im in the process of pulling the engine but if I try and take the jugs off I dont think they will move and I will be stuck???

 

[seadooya]

Had same issue, ended up cracking the sleeves, which you wont see until you remove the cylinder, and to do that, i had to cut the rods in half. Better off, get'n ahold of SBT for engine swap w/ 1yr warranty. Dig the choice of tools to throw at it...:reddevil:

 

[Dennis]

I agree with SEADOOYA. If the pistons are rusted that bad then the crankshaft is probably junk also. It's SBT time.

DAWG

 

[Dr Honda]

yup... new engine time.

also... once you beat on the pistons that hard... you probably flared out the tops (by crushing the piston face) and now they are really stuck.

 

[schlik83]

thats what i thought... Will sbt still take it as a core with it siezed up like this?

 

[seadooya]

yup.....only extra charge you'll get is if it has cracked casing/s, other than that, they dont care about sleeves, condition of crank..etc. best way, bud.:cheers:

 

[schlik83]

A coulpe older guys told me that they know for a fact brake fluid will break the pistons loose in a day or two of soaking...

And they said that using diesel fuel would have a good chance of working also...


Has anyone had any success with these??? They were really sure about the brake fluid working..

 

[seadooya]

give it a shot...what you got to lose.

 

[ProbeGT]

50/50 mix of acetone and trans fluid is also very good.

to unseize stuff like that you need a fluid that is very thin and clear. Trans fluid alone is still too thick.

 

[voodoo]

Once you get it apart you may be able to clean it up and see the crack/s, maybe not, there is no fluid to fix cracks.

 

[Bills86e]

I have used my construction pin driver, a power actuated Ramset, to bust pistons up. Its dangerous and pieces fly, and you need eye protection. It works for me, but I am an experienced pro tradesman. Bill

 

[magical]

i've used deisel on a petrol car engine left it for 2 days then tow'd car and it free'd rite up