Oil Vapor /Smell from Aircon Vent [Archive] - Bimmerfest - BMW Forums

: Oil Vapor /Smell from Aircon Vent

07-01-2012, 08:58 AM

I have a strange problem with my 2006 BMW 730Li. After driving the car for awhile, my car will intermittently have a faint greasy smell in the cabin The most apparent will be an oily smell on my hand as it is closest to the aircon vent.

I've sent the car to different mechanics and all says the car is running fine with no oil leaks detected under the hood. The most frustrating part is whenever the mechanics test drive it, the problem will not occur!

After searching all the relevant forums, could this possibly be a failed CCV, gasket leak or evaporator leak? I'm planning to just ask the mechanic to replace whatever most likely component to cause the problem. Hopefully this problem will be resolved. I know the evaporator replacement will be very costly so I need to be very sure about this.

Thanks in advance for any advice. This is a great forum and I've learned a lot from fellow members!

07-02-2012, 03:15 PM
This is just a guess!..... The only thing that comes to mind is the drivers side air intake, it sits directly above the brake reservoir and booster. Could it be brake fluid that your smelling? Open the bonnet and remove the drivers side air intake cover/pollen filter, underneath is the brake booster and reservoir, check around there for leaks.

Another thing, are you able to detect the smell on the driver and passenger side, by putting your hand in front of the vent like you said?

Does this occur when you have the aircon on? does the aircon work OK i.e. nice and cold?


07-03-2012, 06:55 AM
Thanks for the advice.

I've checked the brake reservoir and it looks clean. The aircon is cold.

I visited an aircon mechanic today and his advice is to clean the coil but problem is this will involved taking out the entire dashboad and console. I don't think I'm ready for that! I'm now tempted to try removing the blower myself for inspection. Based on my internet research, it seems to be doable and is accessible by removing the glove box. Anyone has done this before on a E66? Is it really simple or a pain?