xijonix

Hey there, for a few months now I have been having a clicking sound from my engine. It is on the driver side of the engine. The clicking/knocking sound is more noticeable when parked on a slope where the front of the vehicle is angled downwards by a bit. You could hear the clicking sound when it is angled downwards around 500RPM, when still parked you rev the engine to around 1500 rpm and release off the pedel you can hear it louder then quiets down a bit as the rpm drops back to 500. It the sound doesn't get louder when you rev the engine higher, only when the engine decelerates from around 1500RPM to 500RPM. It's been a few months like this, haven't noticed any lag in performance. I have took it to the mercedes dealer locally and the mechanic said it is nothing to worry about however it was hard to fully replicate the incidence there since their parking lot is so levelled. I hope I am not damaging the engine, but I do a lot of driving I do about 15000K a month in driving on my vehicle.

Some info:
2004 Mercedes-Benz C240 4Matic [V6]
175000KM

I do a lot of driving a few high revs here and there and it hasn't gotten worse at all for the 30000KM I drove it, I keep taking it to the Mercedes mechanic every month for them to check it out and they always tell me its normal. Usually at this case I would of expected them to make up something cause the car is out of warranty and their chance to make money off of me but surely it wasn't the case. I do my regular oil changes, noticed in the winter time a huge build up of gunk in the engine, my job requires when I reach my destination to do a few short trips throughout the day so there was condensation build up that caused the engine sludge but as it warmed up now it is all cleared out. I've been getting an oil change every 3000KM to make sure the engine gets cleaned out and try to refrain from an engine flush.

I have been reading through many threads and have seen many things that It can be but in my peculiar case I want to make sure that it isn't the timing chain as it doesn't seem to be skipping as the engine is started but a constant noise.

Glyn M Ruck

Sounds like the purge valve - common - listen carefully. The only way to fix it is to replace it.

xijonix

It doesn't seem to be the purge valve, my purge valve is making a low/tiny consistant ticking sound. Its more towards the engine and like half way down the engine, driver side front of the engine around the valve cover and all the rotary good stuff.

Sounds more like a plastic on metal sound, or plastic on plastic.

Glyn M Ruck

That's a pity. Remove the Poly V Belt to make sure it is none of the accessories.

The M112 engines are usually bullet proof.

Other possible causes.

Timing chain or tensioner.
Small end bearing - we have had a few.
Hydraulic lifter damaged.

Good luck!

xijonix

I know =(, I wish it was the purge valve, as it would be a simple and cheap fix. I regret buying used you never know how the vehicle was treated in the past. My vehicle I recently figured out (I purchased it in September), has $26,000 of insurance claims 5 separate big claims. It also has had 10 previous owners. I don't want to sell it cause it's the best vehicle I have ever driven.

I wish the mb mechanic knew what they are doing. I will see if it becomes more prominent, I will take it to an indy shop.

Thanks a lot for your help, I appreciate your time and I will update you on what I find as the issue.

jaymusic

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