Siezed aluminum piston in an aluminum cylander

dansawyer

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The piston from an SU carborator is siezed in the piston. What is the best way to free it? I have tried penetrating oil and PB blaster a couple of times.
Thanks, Dan
 
That is a tough one. Maybe a heat gun to heat the body. The only other way is just brute force, and it's pretty hard to get to. You would need to pull the main jet and the needle, then use a small punch to drive the slide out.
 
Is the piston seized into the housing or the bell? If the bell, the center shaft of the piston is steel.
 
SU's usually seize from corrosion. Are you able to remove the oil dipper/plunger? ATF might help if you can fill it from the top.

An ultrasonic cleaner might work. Might reach out to Ztherapy, in Salem Or. They are one of the premier rebuilders of SU carbs.

 
I'm with Jim on this one- heat gun or light bulb plus some kind of penetrating solvent or liquid wrench
Did it seize all of a sudden or was it getting sticky over a period of time? If it's the former then it might be a piece of dirt or sand, the latter might be corrosion or fuel deposits
-Mark
 
The carburator was pulled from a working vehicle about 25 years ago; it has been sitting in a box since. There were two carbs, one is normal and one seized. I will try penetrating oil followed by heating the cylinder. Once it moves I assume a light cleaning should smooth things up.
 
You don't say if it seized from corrosion but if that's the case you may be dollars ahead to source a replacement or two.
ATF & Kerosene might get it moving but you have to ask what damage was done by the corrosion.

John
 
I cannot determine why it seized; I assume some form of corrosion. It was not frozen when I pulled it. It has been sitting a garage attic in Oregon, not particularly hot but certainly humid. We are not near the coast so not salty.
 
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