No way bar oil is getting inside the muffler through the oiler. If it's oiling excessively, it could be spraying up onto the muffler, but tha even seems far fetched. What pinhole are you talking about?Yes, I applied seven pounds of pressure with cap off for three minutes using a mityvac and needle remained steady. Could it be a defective oiler excessively lubricating the crankshaft pin hole?
I had a 390XP that I knew had a leak between the tank & crankcase. Took me 3 goes to find it... didn't show up under pressure/vac... didn't make bubbles underwater... only became apparent when everything was hot. Got loctite to whick into it when it was hot & under vacuum & it appears to have fixed it but I haven't put the saw back to work yet.
I did change the gasket and it's sealing, used my thumb to plug it and pressure/vac tested it for three minutes and gauge needle remained steady, but still there's oil coming out of the muffler. Oil/gas mix ratio is fine too. How would you plug it?Its only there to lube the clutch bearing, you need to plug it to do a vac/pressure test. For your bar oil issue you most likely need to replace your crankcase gasket.
I apologize for this earlier post and have asked for it to be deleted and sent an apology via PM. I was not myself when it was made.I thought the crank bearings were lubed with the oil in the fuel. If there is a hole in the crank into the crankcase, how did it not leak during your pres/vac test? OK, you caught one with your trolling BS. Glad the ignore button still works.