Rauhbatz

Hi all...from time to time our 2007 ML 350 emits a smell in the cabin not unlike exhaust fumes. It only happens at idle when stopped during when the heater is in operation.

The dealer could not find anything but did replace the interior air filter. The smell returned this year with the onset of the snow.

Any ideas? I was thinking its a gasket letting go somewhere. On my last oil change ($167 these days!!!) at this dealer they mentioned a few small oil leaks that have popped up...thought that might have something to do with it.

Of course we could move back south to Atlanta and solve this whole problem by never having to use the heater!!!!

BTW our ML has 177,000 miles on it...just put its first High Mileage Award badge proudly on the front...!!

Rauhbatz

BTW, the dealer noticed that I have a small oil leaks around the rear cam caps and centrifuge cover (?)...might that have something to do w this situation?

u001elg

Did you try replacing the cabin air filter again?


I have found on both my ML's that the filters eventually "foul" and will start emitting an odor if left in too long. I have gotten in the habit of replacing them at least once per year or sooner when my wife notices an odor.

Rauhbatz

Hi u001elg....the odd thing about this smell is that it is coming from outside the car. It only happens when it its stopped and the heater is on. I peeked around looking for oil leaks and didn't see anything.

I did notice a slight discoloration where the right exhaust manifold comes out of the block...but I don't think that's anything. I also checked around to see if there is any breach in the exhaust pipes...didn't see much there but I might have the dealer check that out...

My wife says it smells like exchaust fumes but to me it smells a bit like pizza...sort of a rusty type smell.

Very weird.....

Hooray!

My daughters Subaru does this. Hers is related to a slow head gasket weeping oil leak on the hot exhaust. Perhaps related to your small cam cover oil leak? I steam cleaned (carefully) all the oil off her engine and smell went away. The boxster style Subaru engine is notorious for head gasket leaks on the lower half of the horizontal cylinders due to unburnt gas that settles in the cylinders every time you shut off the car. Smells like rusty pizza!

Rauhbatz

Hi Hooray...hope you had a great Christmas! Our ML does smell like rusty pizza...but lately the smell has gone away...as well as the oil leak.

On our drive from Ohio to Miami for vacation (2400 mi total!) I checked the oil on a regular basis. What's odd is that the leak appears to have stopped. Im wondering if when the did the oil change it was filled up just a bit more than needed and excess oil may have been coming off the breather.

Will monitor things over the next few days and report back...but I do think its related to oil coming off the cam covers...dealer mentioned that's where they observed a leak.

webgrammer

If your rear cam plugs are leaking oil, even a small amount, they drip behind the motor and land directly on the cat burning off and producing the smell I believe you are experiencing. At idle the fumes are being sucked into the cabin, whereas at speed they are dilluted by a mass of high speed fresh air. As a 20 year ASE Master tech who specializes in European cars, I highly recommend you fix the oil leak first and see if it cures your problems. If you are handy, these seals are not difficult to replace, all you need is flat tip screwdriver and a mirror.

Rauhbatz

Thought that might be the source of the oil....

I might have a go at this if I can find them. Do you have to drain all of the oil out to change them? If so I may just let the dealer do it when I get the oil changed



Thanks again! We love our ML...183K miles and still going!

C230 Sport Coup

Usually a leaking exhaust gasket.
I've replaced mine many times for just this issue..especially bad wit the header, not sure why.
BUT simply set the heat to recirc and you won't have to breath
exhaust.
Try torquing the exhaust manifold nuts. They get loose over time.