Whining noise from compressor when accelerating

[Dragon]

I have a 2001 SLK200. When I accelerate, I can hear a whining noise like the compressor has a fatigue. Can anyone please give me a clue what wrong? Is there something I can do to obviate this problem? I can hear it noticeably when the vario roof is in place otherwise when it folded I don't hear it.

I recently bought a 2005 W211, it got a newer compressor engine than the 2001 W170. I noticed it quieter than the 2001 W170 during idle. I was around the Basingstoke area last summer and asked the MB dealer why my W170 turbo is so noisy clattering like a diesel at idle. He told me it normal. Is there something I can do to rectify this problem?

 

[grober]

Don't know about your problem with the older car but the w211 has an entirely different engine-e.g. 2 balancer shafts and kompressor- smaller+ different manifold assembly from the the older engine in the w170. Best to compare like with like, you need to get a run in a w170 of a similar age to your one to get a valid comparison. I think they do tend to whine a bit anyway-its a question of how much?? The clattering at idle could be tappets or timing chain problems or just something loose resonating at the idle frequency e.g. exhaust shielding. Is the oil pressure OK-- when was changed /level checked last?

 

[Dragon]

The oil pressure OK and oil changed at recommended intervals. Remember I asked the MB dealer at Basingstoke and he told me the clattering at idle is due to the compressor and that normal. I am wondering how many W170 out there does not clatter at idle?

 

[Will]

I think the R170 SLK200 Kompressor uses the M111 supercharged engine, these all do tend to whine quite noticably (especially with a window open or in your case, the roof down?)

Could be something else if it's whining too much (eg tensioner pulley etc), but most likely nothing of concern - as Grober has said, try and compare to a similar model to your own (SLK, CLK, W202 C class Kompressor models) and see what you think?

Will

 

[Bobby Dazzler]

Bearings don't fail often, but they do fail, and could be one reason for strange noises - but unlikely. A dealer will inevitably suggest a whole replacement supercharger, however the bearings can often be replaced.

Try the US forums, as (A) it's more likely that someone will have encountered the problem, and (B) more likely to have had a go at fixing it, rather than replacing the whole lot. Give www.mbworld.org a go.

 

[Dragon]

If someone can confirm to me the speed of the compressor increases inline with accelerating then I know the compressor is OK although it annoying to hear that whining fatigue noise.

Does the bearing of the compressor needs maintenance?

 

[Dragon]

How do you guys register with MBWorld? I did it once a couple of weeks ago and the registration was asking for the chassis number and I entered WDB170.... and then it said sorry, your car does not exist.

 

[Bobby Dazzler]

I believe the bearing is maintenance free - the supercharger is pretty much a sealed unit if my understanding is correct.

The supercharger is connected to the crank with a belt. A as engine speed rises the crankshaft speed rises, and so the suprcharger speed should increase.

Your supercharger probably has an electronic clutch which engages the supercharger at a certain engine speed, but the drive from the belt would still be there - it just isolates the kompressor internals at low engine speeds, and when in neutral (so it doesn't produce boost).

Someone with more experience of your particular model and engine should be along to confirm if this is the case (or otherwise).

 

[Will]

I believe the the early M111 supercharged engines had the electronic clutch, it used to dis-engage the Kompressor to save wear when at tickover, eg in traffic etc. Apparantly this was deleted on later models, so they ran continuously - although I have never had reason to investigate that.

You'll know if it's got the clutch by looking at the pulley: If the outer part of the pulley does not rotate at idle, then the supercharger is not running. If you build the revs up slowly to around 1500/2000RPM or so, you should hear a click and a change of engine note, plus the pulley should start rotating as the clutch engages.

Just to add also, on my previous W202 which had the 230 Kompressor engine, I had to replace one of the tensioner pulleys as it was whining - having not seen or heard your car, I'd recommend comparing it to another one to see if you think it's making too much or the wrong sorts of noises

You can check if the tensioner is making the noise by briefly jamming it whilst the belt rotates - be careful how you attempt that, but it's the way in which I diagnosed the faulty component.

HTH,

Will

 

[Bazzle]

Yours is an R170.
Generally they all whine a bit, some more than others. Rarely a bearing may fail, SC are noisy esp on pre 2000 models.
The idler next to SC fails too, eay to swap out (one with black plastic roller)
Yes the whine is relative to engine speed.

Go to THIS MB Forum for help.
http://www.benzworld.org/forums/r170-slk-class/

Bazzle

 

[Dragon]

Many thanks to all who contributed. I did have a skim over the MBWorld website. The likely cause is the pulley bearing. I had a look in the MB electronic DVD manual I bought at eBay, there is no bearing associated with the compressor pulley but 3 curved washers. There is one associated with the crankshaft and this is the most likey cause. There is a bearing in the compressor and as the compressor is a sealed unit I gathered from another thread, there is nothing much I can do. Do I have to change this crankshaft pulley bearing now or face consequences if it breaks to pieces on the road?

 

[Bazzle]

What makes you think it is a bearing?
How long have you had it?
Check the plastic idler bearing 1st.
All the SC bearings can be changed out.
If yours {post 2000} has the NO clutch nose the rattling is prob the hard phenolic drive adaptor ratting inside. Easy fix.

Bazzle

 

[Dragon]

I noticed the whining noise come into being when I was accelerating from 60 mph onward. I had it for 4 years and was already 3 years old when I bought it. It definitely post 2000 because of the signal indicator on the wing mirrors. The pulley associated with the compressor always turning whether it being driven or idle.

I was reminded to change the serpentine belts when I took it to MB dealer in July last year which I did in November. As I said I checked the electronic manual there are no bearing associated with the compressor pulley. The only bearing is the crankshaft. MBWorld website have many links about whining noise and they said the pulley bearing.

If I am wrong what do I have to do to get rid of the whining noise?

 

[Will]

I think it's most likely going to be the tensioner pulley. There is a bearing inside this which would cause an excessive whine, happened on my old C230K as posted above.

You can see it in this picture which I found on the web

-------------------------------^^^^--------------------------------

It's in the picture as above, just above the chevrons (^^)
They are easy to remove and replace, you could probably stall it with a pry bar whilst the engine is running to diagnose it, or possibly you might be able to try and remove it and briefly run without?

They're only about £20 or so from memory. One hex bolt holding them on, easy job

Will

 

[Bazzle]

One last thing.. IF it has leaked out the sealed lube oil the gears in the front can get noisy.
You have to remove SC to check oil as the plug is below fill level with the way they are mounted on slk and the oil if still there will run out when you open plug bolt.

Bazzle

 

[steveandemma]

tensioner pulley

Hi. Im confused by the picture which is the tensioner pulley? thanks steve

 

[Will]

Hi Steve,

It's above the series of arrows (^^^) underneath the picture in my post. Looking back on my post it might be better described as an 'idler' or similar. The small round pulley that doesn't otherwise directly drive anything.

Will

 

[steveandemma]

Hi Will
The text and the chevrons are not under the picture on my broswer. They are to the left of it. Is the pulley near the bottom of the picture in the middle? So can this make the engine whine. on my engine it is very loud.

Thanks
Steve

 

[Will]

Second one in from the left, the small black 'wheel'

 

[steveandemma]

Thanks. So can this make a loud whining noise at idle and when driving?

Cheers
Steve