Strange noise, burning electric smell and smoke
Another issue with my E55. A few weeks ago after starting a car I've noticed a strange noise, kind of like grinding or screeching (not sure how to describe it) coming from the front of the car. It happens occasionally, not with every start. Also noticed that it happenes when engine is already warm. This week, after driving a short distance, enough to get the engine to the fully operational temperature, car set for about an hour before I started it again. This time when I started the car, the noise happened following by a white smoke coming from under the hood on the drivers side. I have killed the car and popped the hood. There was a burned electrical smell. Removed plastic fuse cover in hopes to find the source of smoke. No luck! Came back an hour later for a closer look, in hopes that another person could listen under the hood as I crank the car a few times. Nothing! No noise, no smoke, no smell. No lights on the dash. Scanner didn't show anything. Although, I don't really know which module to look at.
Forward two days–no problems. Every time I star the car, I listen intently for the noise. Nothing from a cold start. But when I started the car again on a fully warm engine, I've heard the noise followed by electrical burning smell, but no smoke. Thankfully, drive home was less than a mile. Parked, looked under the hood for any spills of fluids, wet spots, melted wires... Nothing! I will mention that the car does have a slow oil leak what seems to be from the oil drain plug.
Scanned the forums for any information that could point to the causes, but no luck.
Any of you experience anything like this? Suggestions, beside going to the dealer.
Thank you.




Sounds like one of the pulleys is seizing up.
Look for black belt dust under the hood for confirmation.
Next time it happens, turn off car and remove serpentine belt and restart with belt removed to see if noise is gone. (Obviously only run the car beltless for a couple seconds)
Check all pulleys as suggested above as well as the idler, tensioner, and A/C compressor.
In regards to a serpentine belt and pulleys. They have been replaced last year. Not to say something couldn't be out of place though. I'll have to take a closer look.
What makes diagnosing the issue problematic is that it only happens for a split second and then the noise is gone and doesn't repeat itself until who knows when.


Last edited by BetterDaze; Aug 8, 2023 at 06:58 PM.
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By the looks of it, mp4 video format is not supported. So I've attached a couple of screenshots.
First picture has arrows pointing to the area where the smoke/mist comes from. I say mist because when it happens, it is almost like a shot of NOS. Which leads me to believe that whatever is the cause it is under pressure.
In the picture above you can see steam/smoke coming from under the coolant reservoir area (top left corner of the picture).
Hoping this might give someone an idea of what might be the cause of this.




I know that coolant is pressurized when hot. Wondering if it could shoot a fine mist like that?
Ps. Suggestions on how I can upload a 5-10 second video in here?
Thanks




Fingers crossed is that simple, though if crumbling likely new reservoir and new hose.
Please! I cannot even get the GM to return my calls! I have been invisible to MY Local Mercedes Benz
Dealership!
Last edited by lovemy#3MBZ; Jan 9, 2024 at 02:20 PM.



To answer your question, no major puddles.





