The International Cessna^® 170 Association

My oil filler gasket seems to have just started leaking and blowing oil out. The gasket is fairly new but does not seem to snug itself down now as I think it should.
1st question is does anyone know the proper size gasket? I have not been able to locate a size anywhere.
2nd - Can I double gasket to increase the thickness of the gasket? It looks to be 2 1/4 inch OD like the gas cap gaskets.
I'm concerned that there could be an obstruction somewhere. The breather tube seems clear and functioning as I am getting some drainage out, just not like before, but now it is blowing most of the the gunky stuff out my oil filler neck/ oil cap.
Thanks for any advise.

The gasket I used to replace my old oil filler cap gasket was a perfect-fit replacement, and is the same offered as the gas cap gasket by Spruce. Their pn:FC2651, $1.50 (877-477-7823)

Check that the crancase breather is clear. You can even do it by yourself--get a hose that fits the breather tube,run it up by the oil filler neck,blow in it & feel for the air coming out that the oil filler.
You can do the same trick at each fuel filler to make sure the fuel vent is clear.

Eric

A better method, in my opinion, is to use a suction blow-gun or a vacuum cleaner to apply a vacuum to the vent. That way you don't risk blowing any obstructions into the engine or fuel system, neither do you risk over-pressurizing the prop flange seal and causing an oil leak. (I know, of course, that no one would try this without first removing the filler caps/fuel caps, but you never know if the fluid level is above the base of the filler neck, and if so it might drastically pressurize the system.)
If the system is clear, it's easy to hear the suction or vacuum running from the filler neck.