snopercod
Well Known Member
As I was doing my pre-flight runup on Thursday I noticed some brownish fluid gurgling up behind the glass of my mechanical MAP gauge. The level went from zero to 1/4" depending on engine RPM. The fluid looked like gas with some oil in it. This gauge is connected via 1/8" aluminum tubing from the panel to the firewall, and a -4 flexhose from there to the intake manifold of the #3 cylinder of my O-290-D2. I have 160 hours on my plane and have never seen this before. I'm guessing it's just condensed fuel vapors from the manifold, but then the last time I had the intake tubes off there was a lot of black gunky stuff in there (see below). I was told this gunk was "normal", but I'm not so sure. Anybody have any thoughts on this situation?