Just bought a 2005 CL500 and it has a moan coming from the engine bay which goes up and down with RPM. Once underway and settled into a cruise you can't hear it so it's not too disturbing at the moment.

I've already replaced the alternator because that had an actual issue which has now been rectified and it made no difference to the moaning.

Is there a common failure with these cars, it's low mileage and well serviced.

The other possibilities I'm aware of are:

1. One of the idler pulleys
2. Power steering pump
3. Air conditioning compressor
4. Something else

I did spin all the various pulleys when I changed the alternator and there was nothing particularly obviously noisy at that point.

 

Congrats on your new car!

How is the ABC pressure doing?

Please update your profile's details with your newest addition.

 

No idea how to check ABC pressure.

Any comments on the main question?

 

You can check that with DAS. Are you having any ABC errors?

I can't seem to see the main question, could you post it again?

 

Not getting any ABC errors

Just bought a 2005 CL500 and it has a moan coming from the engine bay which goes up and down with RPM. Once underway and settled into a cruise you can't hear it so it's not too disturbing at the moment.

I've already replaced the alternator because that had an actual issue which has now been rectified and it made no difference to the moaning.

Is there a common failure with these cars, it's low mileage and well serviced.

The other possibilities I'm aware of are:

1. One of the idler pulleys
2. Power steering pump
3. Air conditioning compressor
4. Something else

I did spin all the various pulleys when I changed the alternator and there was nothing particularly obviously noisy at that point.

 

Sorry I misphrased my last response.

I do understand the question you're asking now.
There is, ABC. Is it dealer serviced?

 

Do you think it makes a difference if the ABC is being serviced by a dealer or an experienced independent mechanic. I prefer the experienced independent mechanic with lots of ABC knowledge over a modern dealership with newly hired technicians that never had any experience with the ABC system....
Are you a moderator for this site, since you are asking him to provide information that are usually asked by the moderator....???

 

Yes it does, you'll need toe independent mechanic. If it has been serviced by a dealer, you'd want to get a proper ABC maintenance. The mechanics at the dealers get told that the system doesn't need any maintenance at all, so thats bad

I'm not, but I come across a lot of posts when answering people, and I can't remember all of their cars XD

 

I think I've worked out what this is. There was a Mercedes technical bulletin for the pulsation damper. It's going to cost about £60 for the part and should be pretty easy to change.

The noise you can hear when this guy first starts the car (before he revs it) is the same as what I hear.


This topic covers it and has the TSB attached: abc pump or power steering whinning noise Please help - MBWorld.org Forums

 

Interesting!
Thanks for sharing!