Mailing List flyrotary@lancaironline.net Message #67955
From: Ken Powell kenpowell@comcast.net <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Best chemical for stuck apex seals
Date: Fri, 12 Dec 2025 19:08:37 -0600 (CST)
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Voice from the past here...  I would use a 50/50 mixture of acetone and ATF.  It has worked well for me in the past when restoring old dirt bikes.

Ken Powell 501-847-4721

On 12/12/2025 4:43 PM CST Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

 
I'm finally getting around to getting my RV-3B with its 13B flying again. Hasn't flown for 4 years or more.

I can turn the engine by hand but several of the apex seals are stuck -- won't move (back out) when pushing with a wood rod through leading sparkplug holes.

What's the best to spray in there to loosen them up/? WD-40?

I'm reluctant to use carb or brake cleaner -- might they degrade the rubber corner seals or maybe o-rings?

Finn



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