It's a
4 cycle OS with a
tongue muffler? I'd like to see a picture of that.
A picture might not be a bad idea anyway, as it would show the setup, cowling if any, and hoses. Most guys that ran 4 strokes hooked the pressure tap on the muffler to the crankcase drain...not saying that's a good thing to do, but many did. Personally, I think it makes more sense to hook the muffler tap to the tank and a drain tube to the blow-by drain fitting. If it's cowled, maybe it needs more cooling air.
I'll admit that I've never run a 4 stroke glow engine, but it just doesn't seem right to have the bottom end lubed by the fuel. Doing that is just crazy...it does work for awhile, but sometimes the plastic backplate melts and messes up an official flight at the NATS.

Steve