Engine venting after shut down, what ya think?

[Dan Thomas]

It's doubt it's a sticky O-ring that's holding it on there but I'll check that.

It seems like metal expansion and contraction. I can put it on loose and it will become tight as **** as I fly it.

The wrong O-ring material will expand with heat and get really tight.

Silicone O-rings work the best in that application. And the cap doesn't need to be wound up tight like some guys do. I wish Lycoming had just used a quarter-turn affair on that cap instead of the thread. Can't overtighten a bayonet-style fastener.