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During a pre-flight inspection I noticed what appeared to be exhaust stain on the inside of the cowling. It looked to be adjacent to where the 3 left exhaust stacks plug into the muffler.
Right side does not show any stain.
Stacks are fully inserted into the muffler up to the welded-on stop. No obvious cracks or holes in the muffler.
Has anyone else experienced exhaust leakage in this area? If so how to fix as there are no gaskets at this joint?
This is a common problem - I tried various sealing methods including exhaust/muffler sealant, etc., but they all burn out and blow out rather quickly. When CAMit (the alternative Jabiru manufacturer) was in business, they sold a seal kit which I installed and it works pretty well, but unfortunately, CAMit went out of business and I'm not aware of any other source:
If it is not damaging the cowl due to heat, you probably just have to live with it. If it is blistering or damaging the cowl, then I'd apply some sort of reflective heat barrier to the inside of the cowl (such as used to protect against heat from catalytic converters, etc.) to protect it.
Grant, I am having the same problem with mine, same side.. So far it has just blown a bunch of black soot on my cowling and oil cooler.. I was running very rich for a while and it really made a mess. I have re-jetted and things are much better. I tried removing the exhaust springs and tightening up the fit, without much luck. Like John says, guess we just have to live with it.. Other than that I am loving my Gen4 3300, I have a little over 110 hours on it and she is running great.. Happy Flying,
I am going through the same re-jetting. What did you finally end up using for main jet and needle jet?
Apparently there has been at least some success with using a Sonex exhaust. The premise is that it produces less back pressure, being straight. It doesn't eliminate the problem, just reduces it.