Benzoid1

About 5 months ago my inde MB mechanic told me that I needed to change out the intake manifold on my 2007 E350, I did not notice the car idling rough or any problems, ran a scan and all systems checked out. A few weeks ago while I was at a stop light I notice smoke coming from under the hood on the passenger side, seen the smoke again yesterday. Looked under hood from when I got home and saw where the smoke is coming from, looks like a 02 sensor. Looks like the wire insulation the leads to the part has oil on it but I did not find any oil leaks. Would this have any thing to do with the flaps in the intake manifold not opening and closing properly?

Attached a pic of part that smoke is coming from.

Plutoe

No-----as you know the O2 sensor is in the exhaust and as you know that typically gets very hot. When a combustible like oil comes in contact with a hot surface there is typically smoke before a fire.

It sounds like you are very observant you see and smell smoke but unable to locate the source by looking down at the engine----you indicate that there appears to be no leaks----think about that for a minute no leaks but there is smoke---you can continue to believe your self until you have a car fire and then you still won't see a leak---therefore if that really is the case no leak but smoke-----why worry, just make sure your comprehensive is up to date.

If that is not the case why not simply put the car on a lift and have a responsible person help find a leak, because I don't believe you---there is a leak, you just can't see it from your vantage point!!

Benzoid1

Thanks for your input Pluto, after a second look oil may be coming from the leaky oil cover gaskets and draining down the O2 harness wire.