Hi everybody,

I am having an issue (or 2) with my C55 from 2005 (125000km). Some weeks after I bought the car it started making a very high squeeling noice everytime that I start the engine (engine cold). After 5-10 seconds the ugly sound goes away and the engine runs proper after that.

A while later I got a red notification on my dashboard while I was driving: "Battery Alternator Visit Workshop". I took my OBD2Bluetooth device and monitored the Battery Voltage with the "Torque"-App I have installed on my Android phone --> the voltage was oscillating between 13,5 and 10,7V at the beginning,... some minutes later it stopped charging totally and the voltage was at 12,1V and going down.

The next day I started the engine again and got the same squeeling sound during the first seconds but the alternator was charging again normally at 13,6V constantly, so I thought OK. I went for a drive but the red battery light came again after more or less 30 minutes and the alternator broke down again.

First question here --> is this the voltage regulator or is it more in the hardware of the Alternator?
Second question --> is the squeeling sound coming from the alternator? Even with the hood open when I start the car I can not tell for 100% that it is the alternator that is making this horrible noise. If it is only the Voltage Regulator that is broken I suppose the squeeling sound is not from the alternator? Maybe the waterpump?

Anyway I decided to take the alternator out to get it checked in a workshop, but I have a question on how to untension the Poly-V-Belt on the engine. I bought the following manual (which is in fact the WIS/ASRA for all Mercedes C): http://www.emanualonline.com/Cars/Me...ce-Manual.html. This is the tensioner I have on my car (according to WIS this is the new version):


You can see the belt is already off (I also unscrewed the electric fan to make room to be able to unscrew the tensioner pulley) because I just unscrewed the pulley and pulled of the pulley because I thought this was the way to do it. This is how WIS decribes the process of untensioning the belt:


I have to follow the "New Version (B)" instruction. What I do not understand is why I have to "lock" the tensioning pulley? How would the belt come off then? Also what I dont understand is how to tension it again when I will put a new belt on it. When I "unlock" it, does it jumps at the right tension again? This is not described in WIS.

I have explained my problem thoroughly so maybe other people with the same question/problem can benefit from this post.

 

So you weren't supposed to remove the tensioner pulley...but that's okay, gotta learn somewhere. See that "nub" on the bottom left of your picture? You take a 17mm socket on a ratchet, the longer the ratchet the better as you need a good amount of leverage. Turn it counter clockwise and the entire tensioner will move so that you can slip the belt off at the idler pulley at the top and then pull everything off. The "locking" mechanism isn't necessary but can make it easier to put the belt back on. When you tension it by turning counter clockwise, you can slip a 5mm allen key in there to keep it turned so you can just slip the belt back on, then tension with the 17mm socket and pull the key out and let the tensioner move back and tension the belt. I hope that made sense, I tried to describe it as best as I could.

As for your squealing noise, you may need a new drive belt. Based on our description of "squealing," and what I think the noise is you are referring to, I'm 99.9% sure it's your drive belt. When pulleys go bad they don't squeal, they whine.

As for the alternator issue, it sounds like it's your voltage regulator.

 

Hi Petar,

Thanks a lot for your answer! Especially based on experience

The explanation about the tensioner pulley made a lot of sense, it is really easy, if only I knew this before I took off the pulley. Can I just install the pulley back without replacing it with the same bolt?

I will change the belt anyhow so hopefully this horrible sound will go away. I only wonder what the difference is between squealing and whining Do you mean by whining that the sound is there in every rpm constantly, but not too loudly,... and with squealing that it is there very short but very loud?

Ok, would be great if it is only the voltage regulator. How can I be sure it is the voltage regulator and not something else inside of the alternator? I am asking because when I now order a voltage regulator and test it and the problem doesnt goes away I have to order a total alternator with an extra voltage regulator

Thanks,
Pieter

 

What do you mean by "replace it without replacing the same bolt?"

Squealing is high pitched:
Whining is lower pitched and somewhat consistent with the RPMs going up and down:
The idler pulley and belt tensioner pulley are both know to go bad on these cars. If you need a new drive belt, it's recommended you go ahead and change the idler pulley at the same time. From my understanding with the belt tensioner, you can't just replace the pulley on the C55, you have to replace the whole tensioner (or you should replace the tensioner and not just do the pulley). I'm going to replace the belt tensioner soon as PM now that I'm at 104k so I'd just like to have a new one and know I'm good for a while.

When the alternator goes bad, it's the voltage regulator. The wire brushes eventually wear down and stop making contact. It sounds like yours are just worn down to the point where they are barely making contact so it's still working sometimes and sometimes not, and will eventually completely stop making contact. There isn't anything inside the alternator that I know of that you can fix without just replacing the alternator. Seeing as cheap as the regulator is, I would just replace it. I have one I bought last year that hasn't been replaced yet, but I have it just in case because it's a common problem.

 

Hi Petar,

ok I will replace the total tensioner too to be sure. I must say after listening to these youtube movies the sound I am hearing leans more to whining than to squealing actually. I will replace the belt anyhow; so after replacing the Voltage Regulator, V-belt and tensioner, if the noise is still there it can be the waterpump? Because when I now turn the waterpump it makes a very light singing sound, but not close to the sound I hear when I start the engine cold.

Do you know a good website where I can find the part numbers of all these components (when US-partnumbers and EU-partnumbers are the same i.e.)?

I took a picture from the alternator (still installed) because I could not find a productnumber from the side I can look at it. But I guess the Bosch number 0124615014 is the product number of the whole alternator, and not of the regulator:


Can I replace the voltage regulator without taking out the alternator? I guess not because space is limited there?

Thank you so much.

 

Your pics are pretty up close but that looks like the voltage regulator. Here is one site that sells it: http://www.partsgeek.com/gbproducts/...FQMT7Aoda2gAQw

One thing you need to remember about this car is that it has the "Mercedes V8 whine." I don't know why it does it but these cars have a whine, especially pronounced when starting up in cold weather. So it may not be an issue. I wouldn't worry about the water pump pulley unless you are replacing the pump. How many miles are on the car? I'm at 103k and just replaced the water pump. It was just starting to go bad and around 100k is probably good to go ahead and do it as PM.

 

Ok I found one to order in Europe: http://www.ebay.de/itm/MONARK-Regler...item4acc2705fa
--> Bosch number F 00M 145 350; Type: BR 14-M0
--> Can be used for alternator: NC B2 14V 150A 0 124 615 ...

Haha the whine-V8. Yeah mine has it for sure than, it whines really loud when started cold. For at least 10 seconds. Than the whining goes away completely. My car has 120000km (75000miles). How do you notice when the waterpump is getting bad?

 

haha yes, your whine is normal then. Don't worry about it.

As for water pump, read my post in this thread:

https://mbworld.org/forums/c32-amg-c...-workshop.html

And this thread:

https://mbworld.org/forums/c32-amg-c...pump-part.html

Basically, you will probably get the "coolant - visit workshop message." You will notice at lower speeds and idling the temperature will rise slowly but likely won't overheat past 100C. There was one time it freaked me out and started going higher so I blasted the heat on full to pull the heat outta the engine but I was okay. If I had waited longer before replacing it, I'm sure there would have been one day where it would have totally stopped and car overheated and I would have had to turn it off and not be able to drive it. Temp would rise slowly to 100C and then it would kick back down to normal op. It would be intermittent. Some days I would drive and not have an issue, others it would show up every 5-10 mins during the trip. I just replaced it a few weeks ago. It's a big PITA to do but it's pretty straightforward.

 

Perfect! Than I know what I need to do when this trouble code comes up one day

First I repare my alternator that I can drive my car again

Thank you for the help.

 

This site needs a 'This dude is awesome' button so I can click it repeatedly for Petar... always helpful!

 

Haha, thanks man Always happy to help my fellow Benz brothers.

 

Hi Petar!

I changed the voltage regulator and it is working again fine I must say it was not easy to do this here on the street

Thank you very much for the help!

P.

 

Glad to hear it!

I changed my radiator on the street at the last house I lived at since I didn't have a parking spot, that was fun lol