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Old Sep 27, 2017 | 11:12 AM
  #1  
leojhartiv's Avatar
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C43 AMG Coupe
Burning smell coming from engine

I've noticed when I'm driving my 4-month (~3000 miles) C43 coupe with the sunroof open that there's a distinct smell coming from the front of the car. It smells an awful lot like crayons cooking on a radiator (if you remember that sort of thing from elementary school).

In all the times I've noticed, I was in Sport-Plus mode, but not driving particularly aggressively. That said, it might also happen in other modes.

I was curious if this is some sort of "break in" smell or if I might have a problem to check out.

Thanks!
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Old Sep 27, 2017 | 11:51 AM
  #2  
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Saab 900 SET
Originally Posted by leojhartiv
I've noticed when I'm driving my 4-month (~3000 miles) C43 coupe with the sunroof open that there's a distinct smell coming from the front of the car. It smells an awful lot like crayons cooking on a radiator (if you remember that sort of thing from elementary school).

In all the times I've noticed, I was in Sport-Plus mode, but not driving particularly aggressively. That said, it might also happen in other modes.

I was curious if this is some sort of "break in" smell or if I might have a problem to check out.

Thanks!
Does MB ship cars with Cosmoline? Cosmoline is the genericized trademark for a common class of brown wax-like petroleum-based rust inhibitors, typically conforming to United States Military Standard MIL-C-11796C Class 3. They are viscous when freshly applied, have a slight fluorescence, and solidify over time and exposure to air.

It does smell like you described, might be burning off the car!
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Old Sep 27, 2017 | 12:16 PM
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2021 Mercedes C63s AMG Coupe
Originally Posted by leojhartiv
I've noticed when I'm driving my 4-month (~3000 miles) C43 coupe with the sunroof open that there's a distinct smell coming from the front of the car. It smells an awful lot like crayons cooking on a radiator (if you remember that sort of thing from elementary school).

In all the times I've noticed, I was in Sport-Plus mode, but not driving particularly aggressively. That said, it might also happen in other modes.

I was curious if this is some sort of "break in" smell or if I might have a problem to check out.

Thanks!

I think I have noticed exactly what you are describing here multiple times. But for me it happens when I am being stupidly aggressive. The smell as far as I can tell seems to be coming from the transmission area. I would be pretty interested to know what it is. Kinda feels like I am killing the car haha.
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Old Sep 27, 2017 | 01:31 PM
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2017 C43 Coupe
I smell crayons (not really burnt so maybe a different smell) whenever I open the sunroof, I figured it was the grease they put on the rails
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Old Sep 27, 2017 | 01:47 PM
  #5  
munis's Avatar
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2021 Mercedes C63s AMG Coupe
Originally Posted by VCashmo
I smell crayons (not really burnt so maybe a different smell) whenever I open the sunroof, I figured it was the grease they put on the rails
No it definitely does not come from there. I usually get it through my air vents inside the car when the A/C is in the ventilation(non circulation) mode and I am pushing fairly hard.
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Old Sep 27, 2017 | 09:51 PM
  #6  
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From: Markham, Ontario
2020 MB C43 Sedan AMG
I smell coolant from my engine bay area, however, I don't see any leaks.
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Old Sep 28, 2017 | 01:07 PM
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Originally Posted by synergize
Does MB ship cars with Cosmoline? Cosmoline is the genericized trademark for a common class of brown wax-like petroleum-based rust inhibitors, typically conforming to United States Military Standard MIL-C-11796C Class 3. They are viscous when freshly applied, have a slight fluorescence, and solidify over time and exposure to air.

It does smell like you described, might be burning off the car!
Having just changed my oil, pulling the plastic skid plate to access the oil pan, I noticed a lot of what looked like dust caked oil drippings at first. Upon closer inspection and a "wipe & smell", there seemed to be a good portion of bare metal components coated in what I equated to Cosmoline - dirty golden colored, oily/waxy and very specifically applied. Only difference is that I've never smelled anything as described here in 9500mi.
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Old Sep 28, 2017 | 01:46 PM
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i think i smell electrical sometimes. but on my way to work there is a electrical PCB or some sort of plant that always smells like burning electrical.

either way, one day at the track cleared everything out for me. shes going good at 4500 miles right now . just need to fix 2 rattles.
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Old Feb 8, 2018 | 08:29 PM
  #9  
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CLA250
Burning crayon smell when I drive my 2014 cla250.

Originally Posted by leojhartiv
I've noticed when I'm driving my 4-month (~3000 miles) C43 coupe with the sunroof open that there's a distinct smell coming from the front of the car. It smells an awful lot like crayons cooking on a radiator (if you remember that sort of thing from elementary school).

In all the times I've noticed, I was in Sport-Plus mode, but not driving particularly aggressively. That said, it might also happen in other modes.

I was curious if this is some sort of "break in" smell or if I might have a problem to check out.

Thanks!
I am new here and first Benz and trying to figure out this crayon smell before I take it in. Car has 40K miles on it and seems like I am not getting good gas mileage either including this weird smell of crayons.
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Old Feb 9, 2018 | 03:54 PM
  #10  
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From: Lake Forest, CA
C43
I had that once on another car I owned and it turned out to be rats that had crawled up into my engine bay and made a nest. Then they proceeded to chew into and through some wiring harnesses. Have you popped the hood to check it out?
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Old Feb 9, 2018 | 04:58 PM
  #11  
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A Benz and a BMW
I get the crayon smell too when driving the car hard in warm weather. Car was bought new, hasn't been modified, and I don't drive it like a turd by flooring it from red light to red light. I'm assuming it's normal. Unless it's either strong enough to distract you from driving, or present 24/7, I'd just ignore it.
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Old Feb 9, 2018 | 05:03 PM
  #12  
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CLA250
I just purchased this car at a used car dealership around two months ago. Everything looks clean as a whistle like they cleaned the engine with a toothbrush.
Only good thing is i got an extended warranty but the car is not indicating a problem. You would think a smart car like Mercedes would have sensors telling you something is wrong. I thought it could be the cleaning supply they used on the engine and when the engine gets hot it burns off the cleaning solvent. I’m praying it’s nothing serious lol awesome car too ��I also got a car fax with all the maintenance records from Mercedes in LA CA so there were no signs of a lemon car. Also the gas mileage is terrible, thinking it’s linked to the smell.
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Old Apr 24, 2022 | 01:05 PM
  #13  
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From: Palm Springs California
2008 clk350
Crayon smell

Im getting the crayon like burning smell as well and loss of power. Car isnt overheating but feels hot inside. And ive felt or had. This before. It was the catalytic convertors .. To the tune of 1200.00 and now im getting same thing again so i know its the catalytic convertor. What the hell is causing it to go bad again?.
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Old May 5, 2022 | 02:46 PM
  #14  
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C43
Front end on the passenger side right? I had that until around 8000 miles (1.5yr), now it is significantly better but I still smell it sometimes. I told MB and they checked already, everything seems to be okay.
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Old May 5, 2022 | 03:39 PM
  #15  
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From: Palm Springs California
2008 clk350
Originally Posted by Suzilovesmbz
Im getting the crayon like burning smell as well and loss of power. Car isnt overheating but feels hot inside. And ive felt or had. This before. It was the catalytic convertors .. To the tune of 1200.00 and now im getting same thing again so i know its the catalytic convertor. What the hell is causing it to go bad again?.
Replying to my own thread here... It ended up being the achuator to the intake manifold so i just had a whole new factory intake manifold replaced and new gaskets and now everything is all perfect again thank goodness
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