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Stubborn Piston Wrist Pin

PCHunt

Well Known Member
Sponsor
Pulling #4 cyl due to failed exhaust valve. The piston wrist pin is being VERY stubborn.

Looking for a procedure (trick) to push the wrist pin out while the engine is still installed on the plane. Interference from the engine mount and adjacent #2 cylinder is making the job tougher.

Special tool? Heat, if so, how much?

Thanks!!
 
ATS

Aircraft tool supply sells a tool just for that very purpose. Or you could use a c clamp VERY gingerly. It should not take much pressure to push it out.
 
Last edited:
Pulling #4 cyl due to failed exhaust valve. The piston wrist pin is being VERY stubborn.

Looking for a procedure (trick) to push the wrist pin out while the engine is still installed on the plane. Interference from the engine mount and adjacent #2 cylinder is making the job tougher.

Special tool? Heat, if so, how much?

Thanks!!

? If you have a heat gun, use it to heat the piston up to about 600fht
and the pin will push out with ease. You will not hurt the piston or anything
at this temperature! Thanks, Allan..:D
 
Success!

I put Hoppes #9 on and let it soak. That helped.

But the answer (from a local A&P) was to use a rivet gun to semi-gently "coax" it out. (While supporting the piston to prevent damage to the big-end bearing.)

Didn't get to try Allan's idea of heating it, that would have been the next step. [But wondering how to determine when you have reached 600 deg. F. ?]

Allan probably has a tool for that!! :) And you could bet that it would work!

Thanks VAF.....
 
Not higher than 400F

? If you have a heat gun, use it to heat the piston up to about 600fht
and the pin will push out with ease. You will not hurt the piston or anything
at this temperature! Thanks, Allan..:D

Oil will burn off at 400F, like in ring grooves, etc, the piston does not get that hot in operation! So heat it yes, 600F NO.

It will become easy with heating, just heat and push you don't really need some specific temp. What happens is this: the piston was running hot, oil deposits built up in the gap when hot and now (when cool) has squeezed (shrunk) onto the pin.
 
Agree with Bill. 400F ok, 600F not recommended.

WD40, gentle heat, work it back and forth with gentle pressure, should come out.
 
ATS Tool

I have the $69 Aircraft Tool Supply piston pin removal tool. It has worked great so far and you don't put any side load on the rod & bearings.
 
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