Caliper Piston Will not move....Help...

Ok I have a 1986 XJ700 and am rebuilding the front brakes and brake lines.
Well I was able to remove one piston and the other will not budge.
I Have rebuilt the one side and clamped it down. Then I hit it with 100PSI air and doesnt move.
Is there a chemical to attack the o-rings that are existing ?
The piston is raised up about 1/4" should I push it back in to see if that will free it ?
When I seperating the caliper It was nasty.
Any Suggestions ?
Thanks
Brian

 

There is an easy, safe way to remove the piston. Plug the brake fluid inlet with a bolt and connect a grease gun the the bleed vavle. Pump in the grease and the hydraulic pressure will slowly ooze the piston out. Mine were frozen and this worked like a champ.

 

Cturek,
With this damage the new seals I put in on the other side?
Or could I clean them up and re-use ?
Thanks
Brian

 

I second the grease gun. Just clean everything up and put it back together. Odds are you will at least need a new piston.

 

The pistons get stuck because the aluminum gets corroded between the dust seal and the piston seal. The best way to get it loose is to pry away the dust seal and lube it good with PB Blaster overnight. The next day warm the caliper up with a heat gun and then use your air pressure to pop out that piston.

If its really stuck you'll need to keep the PB Blaster going for a few days then try the heat to expand it so it will let go.

When you get it out look it over good and make sure the piston surface is not pitted from the rust. You may to to buy a new piston if it is pitted.

MN

 

Anything other than a grease gun is doing this the hard way.

 

Ditto.

 

Thanks Everyone for the Info.
I borrowwed a grease gun yeaterday and it leaked more grease than actually went into the caliper.
Going to by my own and give it a go.
I am hoping to give it a try tonight and will let you know.
Thanks Again,
Brian

 

there is another way but it's dangerous you might get hurt, you might break something, the piston might go into orbit never to be found but it will come out
put a few table spoons of water in it, plug all the holes, set it on a kerosene heater crank the heater up
when the water boils to steam the piston comes out VIOLENTLY and some hot water flies
have fun

 

THANK YOU THANK YOU.
IT WORKS...sorry for shouting but I am pumped.
Bought a mini-grease gun for 9.97 and it worked like a charm.
I bolted a piece of metal between the two halves to save some grease.
Now to continue to clean, install new rings and re-install.
I was amazed at how dirty they actually were.
This website is priceless, and charcal for having all the parts I have needed to far.
Brian