SLK idle pulley noise demo

Ikarus · 07-23-2007

Someone on mbslk.de posted this video demonstrating the idle pulley noise that seems to be a common problem with the SLK.

**webslinger** · 07-23-2007

Reeeeaaawwwww!!!

Sounds like you have a cat stuck in there!

:-)

**etyu** · 07-23-2007

It does sound like the whine of a cat.

jliu · 07-23-2007

I have this problem. Taking it into the dealer.

Zut · 07-24-2007

I had this problem but the noise was a little more discreet. MB couldn't find what it was the first time I went. When I had my Service B, they finally found what the source of the noise was. It was an easy fix and at no charge. Now, my baby purrs like a p ussycat (not like a cat with it's tail caught in the door!).

Ikarus · 07-24-2007

Quote:

Originally Posted by Zut

I had this problem but the noise was a little more discreet. Mercedes Benz couldn't find what it was the first time I went. When I had my Service B, they finally found what the source of the noise was. It was an easy fix and at no charge. Now, my baby purrs like a p ussycat (not like a cat with it's tail caught in the door!).

The reason why I am keeping an eye on this is that I'm suspecting mine doesn't sound quite the way it should either, even though it's nowhere near as bad as in the video. My engine has a distinct high-pitched whirring sound to it that dominates the exhaust between 2000 and 4000rpm, especially when the roof is up. My dealer actually replaced one of the idle pulleys, but that didn't help, which might just mean they changed the wrong pulley. The fact that they did agree to doing something about it makes me believe I'm not completely making this up in my mind. I guess I'll try to make a recording of my own and post it here so that you guys can tell me what you think.

Zut · 07-24-2007

Quote:

Originally Posted by Ikarus

The reason why I am keeping an eye on this is that I'm suspecting mine doesn't sound quite the way it should either, even though it's nowhere near as bad as in the video.

Mine was not as bad either. In fact, what they replaced was not the pulley but the belt. It took more than one mechanic to find the source of the problem. It may be a common problem but not all Mercedes Benz mechanics are aware of it, so it seems... I suggest you insist and have them work on it until they find what is wrong. The first time I came with the car, they said that there was no way this problem, whatever it was, could hurt the car, which is good to know.

Ikarus · 07-24-2007

This sound file was recorded with the roof up and the laptop on the passenger seat. Please let me know what you think.

**etyu** · 07-24-2007

It may be the quality of the recording but it doesn't sound bad. Perhaps record the sound with the engine hood/bonnet open.

Zut · 07-24-2007

Quote:

Originally Posted by Ikarus

This sound file was recorded with the roof up and the laptop on the passenger seat. Please let me know what you think.

I agree with etyu. It almost sounds normal but maybe it is just the recording. My belt whirr (which I did not record, unfortunately) was high-pitch and very annoying. I could only hear it while driving at slow speed especially when the engine was cold. At medium speed and up, the normal sound of the engine covered it.

Ikarus · 07-26-2007

Thank you for listening, guys! I have to ask, did you use headphones or a high-quality speaker system? When I listen to it on my laptop speaker it doesn't sound so bad.

I have to say that if this is normal, I'd consider this a stain on the design of this otherwise near-perfect car. I got a passenger perspective on the sound of a Porsche Boxster today and I must say that it sounds a lot better than my SLK. It has this throaty but smooth roar, and there is none of this high-pitched screaming quality that makes my SLK sound like it is easily strained when I push it a little.

**etyu** · 07-26-2007

I listened to it again with shielded computer speakers and with volume set at medium, there is a slight constant hiss in the background (I think just from quality of the recording). The engine sounds almost normal with hardly any clicks. It does sound a little on the higher pitch side rather than being a more throaty or lower pitched sound.

Do you have Green Air Filters? The reason I ask is that after about 5 months with the Green Air Filters, I notice the exhaust sound to be more low pitched than the first 6 months when I got the 280.

Ikarus · 07-26-2007

Quote:

Originally Posted by etyu

The reason I ask is that after about 5 months with the Green Air Filters, I notice the exhaust sound to be more low pitched than the first 6 months when I got the 280.

I'm afraid this would be counter-productive. If the exhaust became lower-pitched, that high-pitched whine from the front would stand out even more.

Zut · 07-26-2007

Quote:

Originally Posted by Ikarus

I have to ask, did you use headphones or a high-quality speaker system? When I listen to it on my laptop speaker it doesn't sound so bad.

The first time, I did listen to your recording on my laptop speakers and it sounded rather normal albeit a little high-pitched for my personal taste. Now that I used a quality headset, I can understand your disappointment. My SLK has a much richer engine sound, although not as beefy as the 55 of course. My whirr problem was different than yours, I am afraid. The unpleasant whining was audible only at low speed. My defective belt theory may not apply to your car unfortunately. If I had your problem, I should return to the dealership, sit with the mechanic in the car, have him carefully listen to the whining and ask him to compare with other SLKs on the lot. Perhaps a simple adjustment will do the trick. I wish you the best.

**dsb** · 07-26-2007

Quote:

Originally Posted by jliu

I have this problem. Taking it into the dealer.

I have a similar problem. It only comes on when starting the car, especially if it's cold. It's not as high pitched though. It also goes away after a few minutes. I think I'll have the dealership check it out during the next service.

jliu · 07-26-2007

Mine was the idler pulley. Replaced it and now the car sounds wonderful again!

Ikarus · 07-26-2007

Quote:

Originally Posted by jliu

Mine was the idler pulley. Replaced it and now the car sounds wonderful again!

Did it sound like the sound file I posted or rather like in the video?

in2dwww · 07-26-2007

Quote:

Originally Posted by Ikarus

This sound file was recorded with the roof up and the laptop on the passenger seat. Please let me know what you think.

That sounds more like a fan is whirring around. Was it hot outside?

jliu · 07-26-2007

Ikarus,

Thats sounds like the beginning stages of an idler pulley issue. The video is of one that is really bad. Mine was sort of inbetween and getting worse towards the video in the last week. Don't forget you are listening to the video with the hood up and the mic in front of the car.

The whine is unmistakeable. Unfortunately you didn't really wind it up ... sounds like you only went to 2000 rpm or something. Could you perhaps make another sound clip and wind it up to at least 3500?

DansSlk · 07-26-2007

Quote:

Originally Posted by dsb

I have a similar problem. It only comes on when starting the car, especially if it's cold. It's not as high pitched though. It also goes away after a few minutes. I think I'll have the dealership check it out during the next service.

Mate,

Having not heard your car i can't be sure of course but that sounds like the secondary air pump.

It activates at engine start when the exhaust temp is low and runs for a minute or two and forces air into the exhaust gas to increase its temperature and heat the cats faster.

If you remove the front section of your airbox its the black box in the middle of the engine behind the oil cooler lines it has a thick black hose coming out of that that splits into a T.

It makes a weird ass noise when its running, i would say pull its plug and test after but it will trip the OBD into granny mode.

07-23-2007	#1 (permalink)
Ikarus Elite SLK World Member Join Date: Jul 2006 Location: NorCal Vehicle: 2006 SLK 280 w. 6M Other Toys: 2000 New Beetle GLS w. 5M Posts: 596 Country: Thanks: 18 Thanked 40 Times in 20 Posts	SLK idle pulley noise demo Someone on mbslk.de posted this video demonstrating the idle pulley noise that seems to be a common problem with the SLK.

07-23-2007	#3 (permalink)
etyu Founding Member #2 / Ambassador Of Good Will Join Date: Jun 2006 Location: Orange County, CA Vehicle: 2008 SLK 55 Posts: 5,280 Country: Thanks: 377 Thanked 277 Times in 168 Posts	It does sound like the whine of a cat. __________________ *Eddy* To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package Designo Black Leather Cover on e-brake handle, ( To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Bill T), SmartTop v1.0, Kleyman 3BFM (NoRegret Custom), Green Air Filters, *Mod. R170 ant.*, EuroClear sidemarkers w/PIAA PlasmaIon lamps, chromed front & rear turn indicator lamps, PIAA SuperPlasmaGTX front parking lamps, bilateral rear fog lamps enabled.

07-23-2007	#4 (permalink)
jliu Founding Member Join Date: Jun 2006 Location: Bay Area, SF Posts: 184 Country: Thanks: 0 Thanked 0 Times in 0 Posts	yeah I have this problem. Taking it into the dealer.

07-24-2007	#8 (permalink)
Ikarus Elite SLK World Member Join Date: Jul 2006 Location: NorCal Vehicle: 2006 SLK 280 w. 6M Other Toys: 2000 New Beetle GLS w. 5M Posts: 596 Country: Thanks: 18 Thanked 40 Times in 20 Posts	Here's how it sounds This sound file was recorded with the roof up and the laptop on the passenger seat. Please let me know what you think.

07-24-2007	#9 (permalink)
etyu Founding Member #2 / Ambassador Of Good Will Join Date: Jun 2006 Location: Orange County, CA Vehicle: 2008 SLK 55 Posts: 5,280 Country: Thanks: 377 Thanked 277 Times in 168 Posts	It may be the quality of the recording but it doesn't sound bad. Perhaps record the sound with the engine hood/bonnet open. __________________ *Eddy* To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package Designo Black Leather Cover on e-brake handle, ( To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Bill T), SmartTop v1.0, Kleyman 3BFM (NoRegret Custom), Green Air Filters, *Mod. R170 ant.*, EuroClear sidemarkers w/PIAA PlasmaIon lamps, chromed front & rear turn indicator lamps, PIAA SuperPlasmaGTX front parking lamps, bilateral rear fog lamps enabled.

07-23-2007	#2 (permalink)
webslinger Elite SLK World Member Join Date: Apr 2007 Location: Bay Area, CA Vehicle: '07 SLK55 AMG Other Toys: Honda motorcycle Posts: 549 Country: Thanks: 22 Thanked 22 Times in 14 Posts	Reeeeaaawwwww!!! Sounds like you have a cat stuck in there! :-)

07-24-2007	#5 (permalink)
Zut Founding Member Join Date: Jun 2006 Location: Montréal QC Vehicle: 2006 SLK350 Posts: 805 Country: Thanks: 0 Thanked 0 Times in 0 Posts	I had this problem but the noise was a little more discreet. MB couldn't find what it was the first time I went. When I had my Service B, they finally found what the source of the noise was. It was an easy fix and at no charge. Now, my baby purrs like a p ussycat (not like a cat with it's tail caught in the door!).

07-26-2007	#11 (permalink)
Ikarus Elite SLK World Member Join Date: Jul 2006 Location: NorCal Vehicle: 2006 SLK 280 w. 6M Other Toys: 2000 New Beetle GLS w. 5M Posts: 596 Country: Thanks: 18 Thanked 40 Times in 20 Posts	Thank you for listening, guys! I have to ask, did you use headphones or a high-quality speaker system? When I listen to it on my laptop speaker it doesn't sound so bad. I have to say that if this is normal, I'd consider this a stain on the design of this otherwise near-perfect car. I got a passenger perspective on the sound of a Porsche Boxster today and I must say that it sounds a lot better than my SLK. It has this throaty but smooth roar, and there is none of this high-pitched screaming quality that makes my SLK sound like it is easily strained when I push it a little.

07-26-2007	#12 (permalink)
etyu Founding Member #2 / Ambassador Of Good Will Join Date: Jun 2006 Location: Orange County, CA Vehicle: 2008 SLK 55 Posts: 5,280 Country: Thanks: 377 Thanked 277 Times in 168 Posts	I listened to it again with shielded computer speakers and with volume set at medium, there is a slight constant hiss in the background (I think just from quality of the recording). The engine sounds almost normal with hardly any clicks. It does sound a little on the higher pitch side rather than being a more throaty or lower pitched sound. Do you have Green Air Filters? The reason I ask is that after about 5 months with the Green Air Filters, I notice the exhaust sound to be more low pitched than the first 6 months when I got the 280. __________________ *Eddy* To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package Designo Black Leather Cover on e-brake handle, ( To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Bill T), SmartTop v1.0, Kleyman 3BFM (NoRegret Custom), Green Air Filters, *Mod. R170 ant.*, EuroClear sidemarkers w/PIAA PlasmaIon lamps, chromed front & rear turn indicator lamps, PIAA SuperPlasmaGTX front parking lamps, bilateral rear fog lamps enabled.

07-26-2007	#16 (permalink)
jliu Founding Member Join Date: Jun 2006 Location: Bay Area, SF Posts: 184 Country: Thanks: 0 Thanked 0 Times in 0 Posts	fixed Mine was the idler pulley. Replaced it and now the car sounds wonderful again!

07-26-2007	#19 (permalink)
jliu Founding Member Join Date: Jun 2006 Location: Bay Area, SF Posts: 184 Country: Thanks: 0 Thanked 0 Times in 0 Posts	sound file vs video Ikarus, Thats sounds like the beginning stages of an idler pulley issue. The video is of one that is really bad. Mine was sort of inbetween and getting worse towards the video in the last week. Don't forget you are listening to the video with the hood up and the mic in front of the car. The whine is unmistakeable. Unfortunately you didn't really wind it up ... sounds like you only went to 2000 rpm or something. Could you perhaps make another sound clip and wind it up to at least 3500?