Very loud clanking noise from engine, belt drive - compressor?
 

2005 C230 67k miles

Whenever the rpms are low like below 800 ( if I put the car in gear (drive or reverse) and I am on the brakes or when I come up to a stoplight), And the A/C is ON , I get this very loud clanking, vibrating and squealing noise from right around the supercharger / belt tensioner pulley and possible the ac compressor. The entire supercharger and air box vibrates like crazy, and if the car is cold enough or the rpms dip enough, it makes a wicked squeaking, like either a seized serpentine belt pulley or something.

This is definitely coming from the front/drivers side engine area...not weak clicking from the a/c vents that alot of people experience.

Weird thing is, the car made this noise before and I thought it was the ac compressor as it went out and then stopped blowing cold. But after replacing the ac compressor (which now works and blows cold air) the noise is still their and maybe even louder.

If anybody has experienced this or has any ideas, please let me know before I start tearing apart this car.

Thanks,

Robert

The belt tensioners go out pretty commonly on these cars. That should be suspect number 1.

This seems to be a problem for this car once it starts getting higher mileage. Mine has 72000 miles and has been making the squealling noise also. I wonder if we can get MBUSA involved since there seems to be such a large group with this common problem. I don't want to replace another compressor again.

I definitely agree with you on this one. Quite a few issues rising with this vehicle at the 60K+ Miles.

I wonder if this is the same noise I have on mine. If it is, mb Tech said don't drive it that much and get it fix as it might affect the belts or have a belt failure while driving. Mine sound like a Disel car metalic knocking. I determine it is on the driver side near the Super Charge cover area. I have a tread open on this noise and had a link to my recording of the sound.

check your sc and idler pulleys. Usually after 60k, the bearings on the idler pullies will make noise. You usually hear them when you do a start cold until the metal expands from heat and it goes away.

When the bearing starts to go really bad, you hear it all the time.

Try taking off your serpentine belt, and spin all the pullies. if it makes noise, it needs to be replaced.

if not, the pulley will eventually seize and play pin ball with your engine bay.

At almost 89,000 miles my 05 C230 doesn't make any of these noises and never has.

Tensioner pulley is likely first culprit as Matt says. Pray it's not an expensive A/C compressor. Compessors usually stop working before they get really noisy.

The noise is a function of the ac compressor as it only makes noise when the ac is ON. But, i think it's more that the ac pulls down the rpms of the motor and that the wicked squeak/ grinding resonates at lower rpm. Also , if you remember, I just replaced my compressor two weeks ago and did a weak diy ( that I still need to freshen up). The car made the noise before the previous compressor went out but not at all while I was driving with the bad compressor.

On most cars, the ecu kicks up the rpms a few hundred when the ac is active, but this car doesn't...

Lucky you ... If you make it to 150 without em, I'll be impressed.

I agree with this diagnosis except for one thing, every pulley I've ever replaced , made noise at all rpms, not just one small region...

Maybe what's happening is that this bad pulley seizes at the low rpm causing the squeak and noises.

I'll check those pulleys again...

I can firmly say the tensioner is very stiff and not a culprit.

So did you have this noise and it go away with an ac compressor swap?

I had the same noise as the OP. I have already replaced the tensioner at 85k and have 130k on my car. So needless to say I was pissed when the noise came back. Well it wasn't the tensioner but the alternator pully. Replaced it and my car has never been as quiet. :nix:

I too was worried about the a/c but it wasn't.

You should have the ECU re flashed. The idle speed should be constant - aircon on or off. The ECU should not bump up the revs, It should maintain them even under the greater load of the aircon. i.e. open the throttle a little under that extra load. This is probably what you mean.

Glyn,

I would have to respectfully disagree with you on this one. True, the noise could be comming from either the tensioner or the idler pulley. I have replaced my idler pulley even though it rotated fine. The tensioner spring is tight with and the pulley has no play.

My researching leads me to believe that the noise is stemming from the alternator (sprag bearing or alternator pulley). As that bearing or pulley binds, it places undue stress on the AC compressor, eventually causing the plastic to break and allow the ac pulley to rotate freely.

For some reason, there are far too many MY2005 W203s with this problem, so I wouldn't call it a random event. When I get back in town from work, I am going to the dealer an have a MB look into the problem. If it is not resolved, I am going to get MBUSA headquarters involved.

-Paul

Let me know if there is something I can do to help.

Let us know how that goes with the dealer and if not MBUSA

Fine - I'm happy to be proven wrong. Experience tells me it is likely a pulley/ tensioner problem. If it goes beyond this I am always prepared to learn of others experience. I've even seen the crank pulley fall apart. (in fairness this damped pulley separation was more prevalent on V6 engines)

Someone look up member Scottisha on here. He has probably the highest mileage MY2005 C230 on here. I can't remember if he ever detailed the symptoms, but he did say that the sprag bearing on the alternator failing took out the A/C compressor. He also said it happened several times to his car.

see the last post here for an update
https://mbworld.org/forums/c-class-w...8l-c230-2.html

Yes, Harmonic Balancer is a known weak point on V6 MLs (W163). The rubber part of the pulley is known to fall apart and cause significant damage to the engine and surrounding components.

+1 A friends C320 had dents all over the engine compartment from a damper pulley failure.

Im trying to catch him! At 136,500 now. I replaced the Alt. pulley, tensioner pulley and the idler pulley in mine already.

well it doesn't sound like the crank pulley is the problem, as I don't have a v6 and by inspection mine looks fine.

But I did happen to get the tensioner pully off today, seperate from the tensioner bracket....without all the work. I also bought a new idler pulley and complete alternator...

Hey e24kgold, did you have the wicked noise were talking about? Why just the alt pulley and not the entire unit, as many say the issue is in the bearings, the "sprag" in particular.

Any way I have update pics here
Attachment 382746

Attachment 382747

While you have everything apart please check your water pump for noise.