Hello Everyone:



For the past 2 weeks I've had an issue with my car. I have a 2001 S55. I've been hearing a squeaking sound from under the hood. To me it sounds like a squeaky wheel that's spinning around.
It doesn't get better after the car warms up & has been driven. I changed the idler pulley within the past year along with the serpentine belt,so my assumption is that's not the problem.
The sound is rather loud & is really starting to drive me crazy.



I know it's hard for someone to diagnose my problem without them hearing it for themselves,but I'm hoping someone has had the same issue as myself & can provide some insight into what's going on.



Thank you all,



Vader

 

So can you lift the hood and take a look inside while the engine is running? Use a narrow rubber hose. Place it next to your ear and place the other end on items you think the noise is coming from while the engine is running. Be careful not to get your fingers or hose close to the moving pulleys and belts. If you are not comfortable doing some sort of investigation yourself then please take it to a mechanic since the squeak could be from any number of things.

 

fan belt or pulleys

 

Do you notice the sound increasing with revs?

If so, it might be tension pulley? The double pulley? I had a sound that squeaks on starts and stays with me around 2.2k to 4k rpm, it goes away after higher gears. About 350-500 bucks depending on shop to fix if that is the one making the squeaks.

 

Thank you all for your responses. I decided to do a more thorough inspection today.I didn't notice it at high revs, only when I was idling. I also noticed after the cold start, when I turned on the AC, it seems like that's when the squeaking starts. Then I turned off the AC, & within 30 seconds or so the sound went away.

I took it out for a a 20 minute drive. Didn't notice it at fast or slow speeds. Went to a drive thru & while I was waiting in the drive thru, it started up again. Started driving again, the sound went away & I didn't hear it at any stop lights.

Sat in front of my house for 5 minutes & it started again. Parked & I turned the engine off. I can hearing the squeaking wine down & stop. Then I turned the engine back on,after a few moments,it starts up again without the AC being on.



Now I opened the hood, took a listen & I narrowed it down to the radiator fan .With the engine off,I manually turned the fan with my finger & I could hear the squeaking as clear as day.


I read that if the AC is turned on the fan runs continually. If the AC is turned off the fan only runs when the engine temperature rises, e.g. when in slow traffic or stopped or when no forced air passes over the radiator.Is that true?



I know a concrete diagnose can't be done without you guys hearing & seeing it for yourselves.

But considering what I have discovered do you guys think the fans just needs to be replaced?

Do I need to replace the radiator fan motor along with the fan?

Or can it be something else?


Thank you all for your time,

Andre

 

Just spray the fan baseplate with lube, no need to change it out

 

Andre,

Be VERY CAREFUL about touching the fan even with the engine off. The fan can start at any time it gets a heat signal from the sensor. Your car may be off but heat rising through a stopped engine can trigger the sensor and start the fan while you are fingering it. You don't want to lose some digits.

 

I sprayed it with lube but I still hear the noise & it's embarrassing. Any other Ideas Guys?

 

Oh Shoot, I didn't know that. Thank you for that info. I'm not trying to loose a finger.

 

You need a new fan. The bearing in the motor is failing. You can not get any of it separately.
Just make sure the key is off and out of the ignition. It will not start. Mercedes do not run the fans with the key off like some other brands. You are going to unplug it anyways.

 

Ok thanks,that's what I assumed.

Andre

 

interesting post！.

 

UPDATE........

I took my car to an independent shop today to have them look at the radiator fan motor. When I explained what the problem was he told me,"It's not the fan motor,but it's the belt that needs to be replaced, let me show you".

He then removed the radiator fan assembly then tells me, "It's not the belt, it's the fan". He then shows me the fan assembly with the belt removed. He spins the fan and you can hear the squeaking sound I was talking about.He then says "It's the bearings in the fan that are going,not the fan motor." He also says it will cost about $700.00 to replace the fan because you can't purchase the fan separate.

My question is, do you guys think this guy knows what he"s talking about as far as the fan needing to be replaced, or is it the motor as I have read in this forum?

Also if so, is that price accurate or should I look for another shop?





Thanks again,

Andre

 

If the fan squeaks when he turns it , it probably is the bearings.

And he is probably correct that it needs to be replaced rather than repaired. You may be able to find one much cheaper used on ebay or the parting out section iof this website

 

Thank you my friend.