Soot on cylinder intake manifold gasket
Doing an inspection to my 3300 Jabiru Engine, with 426h, I have seen soot in the zone, between the intake of the manifold to the cylinder number 3 and the exhaust pipe outlet of cylinder number 5. I checked the bolts but it seems to be properly tightened.
I checked the interior of the cylinders with an endoscope but they look normal.
Could anyone tell me any idea of the cause?
I have pictures but I don't know the way to upload them here.
I'll appreciate any help.
The first thing I would do is to remove the exhaust pipe and check for signs of leaking on the sealing faces.