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Hi I wonder if anyone can offer any advice I have a cls 320cdi 2006, occasionally after a journey, the radiator fan is on when I turn the car off. This is accompanied by a hot rubber smell from the rear wheel arch, according to the temperature sensor the car is not running hot, the rear brakes look fine and the discs are not hot. This is an intermittent problem and happens in cold weather even after a relatively short journey with no traffic, there apperars to be no smell from the engine. The car drives normally but this does seem odd I could understand if it was in hot weather after alot of stop start driving in traffic but not with normal driving in cold weather. Any help would be appreciated
thanks
 

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Hi,

I was wondering if you found out the cause of this problem as I have the exact same problem on my 06 CLS 320 cdi. Heavy fan usage after short journeys with a burning rubber smell coming from near the rear offside tyre. There's also an occasional whirring sound somewhere beneath at the front. I'm now worried to drive it at all until I get it fixed.

Just done some research on here and other forums and it seems that it could well be caused by one of the below. The harmonic balancer and AC Compressor seem to match the symptoms the closest, although the smell comes from the offside rear tyre for me rather than from under the bonnet (not that I know a great deal about what is where). I'm going to see if turning the AC off makes any difference to try and pin it down further.

- Vibration Damper/Harmonic Balancer
- Crankshaft position sensor
- AC Compressor froze up/AC compressor clutch

"Harmonic balancer may fail and damage timing cover"
The rubber bond in the harmonic balancer can decay, which causes the balancer to move and work its way into the timing chain cover. If the balancer comes into contact with the timing cover while the engine is running, it will fracture and damage the timing case and potentially other surrounding parts. The harmonic balancer should be inspected at every service.

"Tire wear caused by worn front thrust link bushings"
Irregular and premature tire wear can be caused by the front thrust link bushings cracking and causing excessive movement in the suspension. The thrust link bushings are fluid-filled (to help reduce vibration), so if they crack, they will leak oil.

"Cracked driveshaft flex discs may cause driveshaft movement/vibration"
A vibration felt through the center floor of the vehicle can be caused by driveshaft flex discs, which crack and shred, causing excessive driveshaft movement. Not repairing these can cause damage to the driveshaft center support bearing, or, in the worst case scenario, damage to the transmission or differential.


Thanks,
Ant
 

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Discussion Starter #3
Hi,
thanks for the relpy
I haven't managed to find anything out so interested to read your comments, my issue is very intermittent, can go for weeks with no problem and then it can happen a few times then go away again. I have had this issue for a couple of years, the car has been in for a service and I have mentioned this on a few occasions but the garage (main dealer) couldn't find anything. The rubber smell is definitely from the rear wheel arch and I can't detect any smell from under the bonnet. Aircon is on all the time and appears to work fine, I have not noticed any vibration or strange noises, a real strange one!
Please let me know if you find anything out as I would really like to find out what is going on
regards
Mike
 

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Hi Mike,

I popped into Kwik-Fit earlier today (only place open on a Sunday I could find) to see if they could shed any light. The easily accessible pulleys and belts all seem to be fine and the mechanic's opinion was that it's normal for Mercs to have the fan still going after you turn the ignition off. I'm not too sure about that myself but am no expert either. What's your opinion?

The one thing that he did spot was that the brake pad on the rear offside tyre wasn't wearing down at the same rate as the one on the rear nearside. His opinion was that the recent extreme weather and salt on the roads can cause a brake caliper to get locked up - hence the burning rubber smell. I hope this is the case and that disassembling the brake, cleaning it and reassembling it will be a simple fix for this. It'd be interesting to know if your rear brake pads are wearing evenly or not.

I'm still worried that this could be caused by something more sinister so I'll take it in to either MB Tech the independent MB specialist in Warrington or the Merc dealer in Manchester ASAP for them to diagnose and maybe do an early service as well. I've had the car for less than 10 days so I'll also be speaking with the independent car saleman I bought it from near Reading tomorrow.

Hopefully, nothing will go pop, bang or set alight on my drive down to North London tonight.

BTW, turning off the air con didn't seem to make any difference to my car's symptoms. Also, like you, the burnt rubber smell is definitely not coming from the bonnet but the rear offside tyre. So far, no rubbing is showing on the tyre. The rubber smell is typically very strong though.

I'll let you know if I find out anymore.

Cheers,
Anthony
 

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Thinking about it, the fact that it's isolated to just the one rear tyre makes me think that it could either be:
- Something fouling that tyre
- That the suspension isn't correct
- That the camber/alignment is off or the wheel is buckled (These seem the most likely).

In which case, I guess I should get the wheel alignment checked as a priority. Have you had yours checked recently?
 

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Discussion Starter #6
Hi Anthony
Thanks for the info, my brakes seem fine, no blueing of the disc (which would indicate binding of the brakes) and the wear seems fine. My friendly mechanic (non MB) said he would at times expect the fan to run on even in the winter due to load from the electrics and the climate control, he also stated that a rubber type smell is not usually from the brakes. I have recently had my rear tyres replaced, wear was even and no evidence of any rubbing of the tyres was noted (incidentally are your rims 18", mine are)
At no time has the temperature guage indicated anything other than normal temperature.
So a bit of a puzzle, let me know how you get on, I am beginning to think this may be normal??

all the best

Mike
 

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Thinking about it, the fact that it's isolated to just the one rear tyre makes me think that it could either be:
- Something fouling that tyre
- That the suspension isn't correct
- That the camber/alignment is off or the wheel is buckled (These seem the most likely).

In which case, I guess I should get the wheel alignment checked as a priority. Have you had yours checked recently?
Hi Ant78 - Quite a coincidence really ! - I am experiencing same symptoms with my 2006CLS 320cdi and seems you must be from my "neck of the woods" too. I have an appointment at MB TECH, Warrington on Monday to investigate problem. Was wondering if you did in fact go to them with this same problem you were having and what the outcome was ? Would very much like to hear from you..cheers, Chris
 

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Hi did you ever get this resolved. I have a 2010 320cdi and the exact same thing happens. The fan runs for some time after stopping and there is a burning smell from the rear wheel arch - very strong.
 

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Hi did you ever get this resolved. I have a 2010 320cdi and the exact same thing happens. The fan runs for some time after stopping and there is a burning smell from the rear wheel arch - very strong.
Hi - Took mine in to MB TECH..thorough check done & nothing found. (checked there was no sticking of brakes etc. which I had suspected) They said that the smell of burning is probably the fact that the fan is blowing the "normal" hot smells from the engine compartment, which does smell rather like a rubber / brake burning smell when standing outside the car after switching off. Continued to monitor..I have come to the conclusion it seems to happen when left idling for any length of time, therefore getting rather hotter than during normal running. EG. - it happens when I drop the wife off shopping / leave car running to keep me warm..when we get home / switch engine off...this is when fan continues to run. She says the answer is for me to switch off and go and help her with the shopping.......I'll put up with the smell thank you very much !...Hope this helps...Cheers - Chris
 

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Thanks. Mine is having to go in later in the week, but looking at various threads there doesnt appear to be a solution that anyone has identified. It reassuring to know the burning rubber smell is perhaps not important (!). Mine occurs after runs of about 4-5 miles of stop start driving and then when I turn off it continues. Enjoy the shopping...
 

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Thanks. Mine is having to go in later in the week, but looking at various threads there doesnt appear to be a solution that anyone has identified. It reassuring to know the burning rubber smell is perhaps not important (!). Mine occurs after runs of about 4-5 miles of stop start driving and then when I turn off it continues. Enjoy the shopping...
Hi - thanks for reply..glad really, cos this tends to confirm my theory / conclusion that it happens when engine has become hotter (or would become hotter if it weren't for the fan) than during normal running (ie - stop/starting/idling). Under these circumstances, there is no flow/blast of air to cool radiator compared with travelling normally (only the fan). Therefore, after switching off, fan continues to run to cool the engine of that "excess" heat. (Mine incidentally runs for approx. 2mins on a fast fan speed, then for approx 2mins slower speed before it stops) I have found that after any "normal" runs, without any idling / stop /starting, (regardless of distance), this fan "problem" never occurs after switch off...I personally think there is absolutely nothing to worry about, and is perfectly normal. Hope I am right !...Regards, Chris
 
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