C-90 oil leak

[cargoflyr69]

I have a C-90 that has a strange leak coming from the airbox. It seems to be a diluted oil/gas mixture. It pools in the bottom of the airbox and leaks and drips out of the front just below where the air filter bracket screws in. This is the same area you'd see raw gas collect whe you flood the engine too.

Where is the oil and gas mix coming from?

Are there any crankcase seals or gaskets that the airbox passes thru to join up with the carb and induction system?


The engine runs fine although a bit tired. It's oil burn is 1qt/5-6 hours

 

[414Flyer]

I think the C90 I flew did the same thing.

 

[Jurassic Jet]

I asked a friend of mine that is an OLD time mechanic with lots of experience on those engines...here is what he said...

That would be diluted oil & gas!!!
Where it comes from is not a leak, but it drains down out of the intake after shutdown

Most likely they are experiencing oil being pulled into the intake thru the intake guides during low power operations, (high intake suction, or low manifold pressure)like running it on the ground, or low powered flight conditions.

It mixes with the un-vaporized fuel from running a little rich perhaps.

They're probably creating the condition by running it to see where it's coming from.

That oil consumption is not bad. Tell them to quit worrying about it and go fly it.

You say the engine is high time. Maybe that is why the intake valves suck a little more oil thru than they should.

Just clean the airbox and go fly