2ng

Hello everyone. I've recently noticed a strange "weeeh" noise proceding from the lower part of the car, next to the rear axle. The car goes nice and nothing appears on the gauge cluster, but I'm curious about it. It is quite similar to the noise that appears on this video just after starting the car, it sounds like something electric.


This noise appears, or that's what I think, when the weather is hot and the car has been working hard, and you can't vary it directly with the throttle or any other thing like the clima, it doesn't matter if it's on or off, it only changes a bit its intensity for a moment when something with high electric consumption turns on increasing the alternator work, for example the xenon lights. It disappears randomly or change its intensity while using the car, and it disappears if you turn off the car for some minutes. What do you think? Considering this background, I suppose it could be something about electric cooling, but what?

Glyn M Ruck

Listen to this clip. Open your hood & listen that way. I hope I'm wrong but it could be the start of Torque Converter/input shaft/bearing/seal/oil pump failure. We have had a number recently.

Glyn M Ruck

Read this thread.

https://mbworld.org/forums/c-class-w...need-help.html

2ng

nope, the "wee" noise does not change its tone when accelerating, it is always the same. It's independent from the engine revs or the gearbox use. It only changes a little bit its tone when something electric is being used, for example, if you hold the windows closing button once the windows are closed , the noise gets a lower tone, if you stop the windows motor the noise gets to the same tone again. I have located the noise, and it comes exactly from the rear axle very close to the differential, and it seems to be nearer to the left wheel. Definitely not from the engine bay or the gearbox

Glyn M Ruck

Great - I'm pleased - We have had too many 722.9 transmissions fail lately & the TC is common.

This is a puzzle. The only thing in that area that could make a noise is the fuel pump. I've never heard a fuel pump make that much noise & it would stop immediately you shut down the car.

It can't be the EECS system (Evapourative emissions control system) that would immediately throw a code.

I think you should get hold of an OBDII scanner & see if the car is storing any codes that are below CEL threshold.

Good luck!

2ng

At first i thought about some engine belt noise, air compresor, alternator, pumps, gearbox etc... but I have checked them and the noise comes from the back part of the car, so I think it's some other strange thing.

2ng

Yes, I'll go to the dealership but with these things it always happens that the car makes no noise when the mechanic is checking it I only was wondering if anyone have had the same problem

Glyn M Ruck

There are many accessories driven by the Poly V belt that could make that noise including tensioners & idlers but you say the noise is at the back of the car.

Look for codes & post them here. It might stop a lot of guessing.

Glyn M Ruck

With these cars you really need to carry an OBDII scanner in the car. It can save you a lot of money.

2ng

Do you know if the Torque application for android reads the error codes from the CLK?

betrezra

power steering pump?

try flush fluid

2ng

the power steering pump is on the engine bay isn't it? and I supose it would sound more when the car is cold because the fluid has less volume. I'll try to get the OBD codes soon and then I'll tell you what happens

Glyn M Ruck

I don't know but whatever you will at minimum require a comms adaptor for the OBDII plug. I would rather use a stand alone scanner.

betrezra

IMHO.... the pitch changes with rpm...... I would "carefully" put a scope (can be a long rod) on each of the accy's...... and listen for the noise....

Options:
Idler pulley (these do go bad)
alternator.... could be bearings going out
water pump
power steering pump
ac unit.... (try with ac on and off)
also check diff trans gears..... park, neutral, drive, rev...... could be a bad tq convertor or low trans fluid......

GL.

2ng

today I haven't had time to get the obd codes checked, but I've recorded this after driving a while when coming home. The noise does not change when reving the engine, and it comes from where I said as you can see:

http://www.youtube.com/watch?v=HoeuV...ature=youtu.be

The ac does not affect, neither the gearbox position or engine rpms and the noise is very very far from the engine bay... it is very strange isn't it? Is there any pump or electromechanical system near that position...? I'm completly confused

ZEEK

thats a very weird sound. I hope someone here can pin point by listening. GL

Efivehundred

Fuel pump?

Glyn M Ruck

The trouble with AMG's is they make so much noise it's hard to tell which sound is bothering you. In the latest clip I hear something that sounds like a chunk of Cat honeycomb rattling in the exhaust.

2ng

I suppose you mean diesels . Apart from the loud awful diesel engine sound, I think the noise is noticeable, the electric like "weee"

Glyn M Ruck

What car are we talking about here?
What is your first post. The car is badged as a CLK55 AMG

Your profile says a 320 CDi. Are we talking about a rebadged diesel? that changes everything?

Do you have a 5 or 7 speed gearbox?
Does your car have Cats & particulate filters???
If it's a diesel then the noise is likely the primary rear fuel pump.
That explains the smoke.

Please confirm which model we are talking about. There are no CLK diesels in the US or SA.

Your car has pre facelift tail lights. Your profile says 2009 CLK -!!!

2ng

I posted the CLK 55 AMG video because it makes some sort of similar strange noise (so I can explain it better, it's not mine, I searched for videos of CLKs on youtube to see if I could find some similar noise), and now I've posted a video of my car (the last one) and the actual noise it makes.

My car is a 320 CDI, the 3.0 v6 diesel with 7g gearbox. Yes, it has diesel particle filter.

Louie D

I am pretty sure that You Tube video was just a reference to the noise the video author is someone totaly different.

2ng

Correct

Glyn M Ruck

OK - Then the noise that is not rev dependent is either the rear fuel pump or the particulate filter regeneration system if the noise is at the rear.

Excuse the confusion.

2ng

My english skills often create a lot of confusions . I've noticed the DPF noise in other occasions, and it's not like this, so I suppose it is the rear fuel pump as you said.

I hate diesel cars... I've spent a fortune on repairs and it has only 100 000 km on the clock, this is my first and last diesel.