Rear Engine Intake Manifold

[Pat Schmitz]

This is both a question, and a heads up to anyone who has a turbocharged 337 (especially those with Riley Intercoolers)

Has anyone else ever had this problem - if not, I would suggest you remove the pilot side rear cowling and inspect soon...

I was working on my plane this evening (cleaning, etc) from my recent trip to the keys, and noticed the inside of my rear cowling was covered in a fine film of what appeared to be aluminum filings (powder)... almost like an overspray from a silver paint would appear.. I knew this was not 'good' and began searching everywhere trying to locate it's source.... What I found was very dissapointing!

From the turbocharger compressor - there is a light aluminum ~3" tube which passes behind the #5 cylinder (pilot side, rear engine, right before the prop). It curves up around the rear of the engine and goes into the intercooler - then onto the throttle body, and then back down to the intake manifold on each cylinder. Where the two pipes pass each other - mine were rubbing together, (aluminum on aluminum) and they had worn the pressurized intake manifold paper thin (it appears a tiny pinhole was blowing out, causing the fine mist of aluminum particals.... When I lightly probed at it with a small screwdriver - it poked right thru!

Now, I need to either find a replacement intake for that section, or find a weld shop that can repair that piece.. It was surprising on the way home that I did not notice any drop in manifold pressure! I did not have my camera, but will take and post a picture soon.