Rubber/plastic burning smell?
Thread Starter
Newbie
Joined: Jul 2012
Posts: 3
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W204 C300
Rubber/plastic burning smell?
I got a second-hand W204 C300. I met a problem. I will meet the rubber burning/ plastic smell when strong driving(over 90miles/hr). I tried the smell is strong in the air-con with internal circle mode, maybe 1~2 mins then the smell disappeared. If I turn off the air-con, no burnig smell. anyone met the same?
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Joined: Mar 2008
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From: 1 hours drive north of Sydney Australia
2007 W204 220CDI Classic Sedan
I got a second-hand W204 C300. I met a problem. I will meet the rubber burning/ plastic smell when strong driving(over 90miles/hr). I tried the smell is strong in the air-con with internal circle mode, maybe 1~2 mins then the smell disappeared. If I turn off the air-con, no burnig smell. anyone met the same?
Thread Starter
Newbie
Joined: Jul 2012
Posts: 3
Likes: 0
W204 C300
Mostly I will smell, from cool car to 90mph. The smell happens 1~2 mins, then disppear. When the car is hot from 90 mph, you won't smell again. I tried to test in different mode as below.
- A/C ON with in-car circle mode, the smell is the most strong
- A/C ON with out circle mode, the smell is not such strong
- A/C OFF with out circle mode, no smell
- Air-con OFF, no smell
I'm thinking it seems that the smell happen with air-con working. Is it possible the instant RPM to higher the voltage to heat up the resistance of the air-con system? Is it possible this is caused by the blower regulator? I just thinking the clue from air-con system.
thx...
Last edited by PHIL2116; Jul 31, 2012 at 11:38 PM.
Senior Member
Joined: Oct 2013
Posts: 418
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From: Edmonton AB
2015 C63S ,DME Tune, KW Has ,Kmac Bushings,BC Forged wheels,Gt Rotors,Porterfield R4S,Modal Intake
Just bringing this back . Did you find the problem ???? my c350 is doing the same thing and it's driving me crazy trying to find it . I've looked at everything under the hood , all wiring and under dash rt side and can't find it but now since playing with wiring and unplugging and replugging it's gone from full time burning smell to intermittent . It does not smell if I put on recirculate and it's not the t/lamps or the back of the cylinder heads . Mines got 20,000 miles
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Super Member
Joined: Oct 2014
Posts: 701
Likes: 103
From: Ontario, Canada
2009 C63 AMG, 2010 C250 4Matic Sport
This, the cover to it is probably leaking.
Here's the new one (right) by the left, you'll see that the old ones seal has sort of flattened out. I was seeping oil quite badly from here and it was dripping onto the right bank catalytic converter, making it smell like an oil refinery inside the car whenever it happened. Replaced the cover and all is well, and has been for the past 40,000km
If no leaks are present from there, check all the rear camshaft seals, they tend to seep as well
Check all of that, you'll probably need a small mirror to inspect all the seals properly. If you don't find anything up top, you'll have to get the car on a lift if there's no oil drops on the ground. Sometimes the panelling under the car will catch any dripping oil, so you'll want to remove them.
Last edited by Funkwagen; Feb 6, 2017 at 08:40 AM.
Super Member
Joined: Oct 2014
Posts: 701
Likes: 103
From: Ontario, Canada
2009 C63 AMG, 2010 C250 4Matic Sport
Super Member
Joined: Oct 2014
Posts: 701
Likes: 103
From: Ontario, Canada
2009 C63 AMG, 2010 C250 4Matic Sport
Found these two - look the same but big price gap?
https://www.amazon.com/Mercedes-Benz...+oil+separator
https://www.amazon.com/Mercedes-Benz...ustomerReviews
What do you think?
https://www.amazon.com/Mercedes-Benz...+oil+separator
https://www.amazon.com/Mercedes-Benz...ustomerReviews
What do you think?
MBWorld Fanatic!
Joined: Apr 2016
Posts: 4,761
Likes: 566
From: Milwaukee, WI
2010 C300 4MATIC........ 2011 C63 AMG.............. 2015 CLS400 4MATIC.....
I know, not sure if its like the wiper blades and filters...made by original company but with the badge on it, it is more expensive. 
Do you have a photo or diagram or reference to where the cover is?
Do you have a photo or diagram or reference to where the cover is?
