560 SEC - Exhaust smell in car

nickbe

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Mar 26, 2009
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Location
Oxford
Your Mercedes
W126 560 SEC
Hi Everyone,

I have been trying to track down an issue in my sadly seldom driven 560 SEC.

I am noticing an exhaust fume smell in the car, it is worst when driving with the sunroof open, although slightly noticeable with the windows open. Strangely enough with the windows and sunroof closed, ventilation or A/C on, there is no problem.

The exhaust system has largely been replaced (with exception of the down pipes) with Mercedes OEM parts (old system was rusty and blowing). Initially I thought the down pipes and / or manifold would be leaking, however there is no exhaust leaking into the engine bay and no oil leaks onto the hot manifold.

Any ideas?

Cheers,

Nick
 

teddycatkin

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Joined
Mar 7, 2008
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Location
cheshire cheese country
Your Mercedes
W107-SL W124-220te W123-230e W201 2.0
Hi Everyone,

I have been trying to track down an issue in my sadly seldom driven 560 SEC.

I am noticing an exhaust fume smell in the car, it is worst when driving with the sunroof open, although slightly noticeable with the windows open. Strangely enough with the windows and sunroof closed, ventilation or A/C on, there is no problem.

The exhaust system has largely been replaced (with exception of the down pipes) with Mercedes OEM parts (old system was rusty and blowing). Initially I thought the down pipes and / or manifold would be leaking, however there is no exhaust leaking into the engine bay and no oil leaks onto the hot manifold.

Any ideas?

Cheers,

Nick

Coul still be the newness of the replaced exhaust sill burning off ?
 

ianstaley

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Jan 8, 2008
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Your Mercedes
ML 270CDi 2001.
Not likely imop, With the windows or the sunroof open you effectively create a underpressure in the car, eg in my old 7 series I didn't need to vac the car (smoker at the time) I just ran the car up to 90 MPH and opened the two front windows, the drivers side about 2 inches and the passengers side full. it just sucked everything out from the front of the car, ash, fag end out the ashtray bits of paper. Clearly in an under pressure cab you will pull air in from any holes in the bulkhead or floor.

So nothing strange about when the air co is on, you are in all essence creating an overpressure in the cab forcing out the air through same hole(s)
I would look for a bulkhead grommet that is not fitting right there are a few quite big ones. also the boot floor has a few I think.

Just start the car let it get to temp and look under the car to see if you get smoke off the pipes. If not, open the bonnet to check for fumes there.
 
Last edited:

Corned

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Your Mercedes
2005 S211 E320CDI Avantgarde
Might also be a good idea to check the integrity of the boot lid seal(s).
 

television

Always remembered RIP
Joined
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Your Mercedes
2002 SL500, 216 CL500, all fully loaded
Could this smell be the engine breathing system leaking fumes, its a sickly smell that taste of burnt fuel
 


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