Hey guys,

Hey RABNEY thanks for posting your idea about just pulling the tensioner pulley instead of having to take off the whole thing. I had been driving with a horrendous scratching noise for months. I went ahead a bought the idler pulley and the whole tensioner but just replaced the idler pulley and the pulley fron the tensioner. The noise is now gone. When I took off the belt. I was able to spin the alternator pulley and I put tension on it up and down and side to side and it felt pretty smooth. I also spun it and it continued to rotate on its own for a while everything felt smooth with no noise or binding anywhere. The idler pulley felt a little weird when turning it and putting pressure on it. I compared it with the new one and the new one felt very smooth. Once out I rotated the idler pulley while putting pressure on it and I could feel the bearings slightly change friction when compared to the new one. The pulley on the tensioner felt fine but I went ahead and replaced it anyways. For anyone doing this. When taking off the idler pulley and replacing make sure the side that has the little square cutouts in the plastic behind the shaped metal spacer goes towards the front, the smooth plastic goes towards the engine. I replaced it backwards and the belt didn't sit right. So far I'm happy with the results, lets see how long it lasts. I still get the weird noise when cold coming from the suppercharger but its the same sound my other supercharged car has so that sound is probably normal.

 

Good, so you didn't need to change the alternator? If so, then the screeching must be the tensioner pulley.

Glad it's fixed

RA

 

Is the idler pulley the one on the alternator? I replace my alternator not even a year ago. I do get flickering of the lights when putting on AC. I just like the others here don't wanna spend carelessly.

 

Is there a way you can change the pulley on the alternator, or is it part of the whole assembly. I had my alternator changed last year... Just dont wanna spend 1k almost for a new one.

I want to fix those idler and tensionner pulleys but dont wanna mess my car up to the point where it's rendered useless.

Any input?

 

same to me, perfect symptoms like mine, i'll hope is not alternator or AC compressor, i trust in: tensioner and idler pulley

 

i solve the problem!! i change idler pulley, belt tensioner, belt and alternator pulley, now car is perfect!
problem was caused by seizur of alternator pulley, then belt tensioner go broken and idler pulley was changed for good measure, fortunately no damage for AC compressor!! thanks guys

 

Did you replace with a Valeo or Bosch?

 

I replaced mines with a Valeo unit. Bought it for $209 i think @ Napa Auto Parts. Box and labels say different but once you take a closer look at the alternator they give you, you see Valeo engraved all over the place.

Hope this helps take the fear off some people with the "1000" dollar alternator price tag

 

I love this thread and Thanks to ALL who posted replies for diagnostic and repairs. I changed the idler (which is NOT the cause of the chirping but because it is so cheap to buy and install I did it anyway. A bad idler CAN and WILL place a load on the accessory drive belt because it is a bearing that will eventually fail. My car has 77K), and I changed the tensionor pulley without removing the compressor (I drilled out the tamper proof center), and I changed the ADP alternator bearing. That bearing is the cause of the low idle because that bearing when seized doesn't disengage when it should, i.e., with AC on and in D or R, therefore putting a heavy load on the engine. The chirping is the the belt slipping and/or one of the other pulleys. Started my car.........brand new! No more low RPM's, no more chirping. DIY is the way to go. I used no special tools because my wife has another C230 that we bring to the stealership so when I brought my alternator in from my C230 they changed the ADP pulley at no charge. 10 min job. Alternator comes out the top of the engine bay.

Any questions at all, PM me. It was just like everyone on this thread is describing. Thanks again.

Dave

 

I have that LOW IDLE issue . So you just replaced that bearing on the alternator and it fix the idle issue? I need to fix that .. its annoying when I stop at stop signs.

 

In my case, the seized ADP bearing on the alternator on cold starts was causing my low idle issue because of the load placed on the the belt. The seizing tensioner pulley and the older idler pulley was also cause excess load contributing to the low idle. I believe there was another thread related to this one where one member said that when the engine heated up the low idle and the screeching went away. That also happened to me. I supposed because once the engine compartment heated, it also heated all of the grime inside of the bearing to allow it to move freely enough to operate at a normal enough level. Let me know how yours turns out.

 

its interested, i had this issue for a while as the chirping noise seemed like it was coming from the right side of the car when the a/c was turned on. i told my shop i think it may have to do with the alternator and or idler pulley, however they did not swap those out. it was actually the blower motor that was created the chirping/hissing noise. i guess its just something to keep in mind

 

if/when my car starts chirping, i'll keep that in mind. Thanks for the post.

 

Hi guys, this is a great thread. I went the easy route to start and changed my idler and tensioner pulleys, but I'm still getting the chirping when the car is "cold" and AC is on...I have no chirping sound after the car has been running for 5 minutes.

Do you think I should try changing the entire tensioner? (part #2712000270)
Alternator pulley?
Thanks!

 

Please forgive me if I sound ignorant but I don't understand the physics to why a bad sprag bearing will damage the compressor as lilbenz230 had mentioned? A sprag is basically a one-way clutch, if it locks up it'll allow the stator shaft to spin all the time and if it free-wheels it won't spin the shaft at all, how will this damage the AC compressor? Also I read somewhere that the compressor is a swash plate type that is "on all the time", I don't think this is correct either as there is a wire coming out the back of the pulley, this means that there is a clutch coil there somewhere allowing the compressor to be engaged and disengaged by the driver or the temperature control at any given time. If I'm not correct please forgive my ignorance but any explaination would be greatly appreciated as I'm hearing a noise at idle and the stealership told me it was the alternator bearing and I don't want to destroy my compressor if I don't fix it for a while, thank you.
I have a 2005 W203 C230 Kompressor sedan (US).
Alan.

 

Are you saying that the alternator is supposed to "disengage" when the AC is on? What causes it to disengage as dsawczyn had mentioned above? A good sprague bearing? How does the alternator charge if it is disengaged, I'm confused.

Alan.

 

I have the screeching of the ac problem and then the noises stopped as well as cold air please help, could some one please tell what is exactly wrong and what would be the most affordable fix

 

You'll need to start the car up and see if the AC compressor is turning or if the belt is even there. If the belt is broken, before you change it you'll need to find out what broke it. Shut the engine off and spin each pulley by hand, all of them should spin quite freely. The AC compressor, the alternator and the power steering pulley should spin quite freely in one direction and have some drag in the other.

 

Maybe I missed it, but is there a DIY for changing the alternator pulley?

 

Pretty much self-explanatory:
Hold the shaft with a Torx bit, use the special spline tool to unscrew the pulley.

BUT, the pulley itself is about $60, plus the tool...
After a while, I bet you will have to replace the voltage regulator due to its age. Another what, $70?

A reman alternator costs about $120-180.

 

OK, thanks.
Is it possible to do without removing the alternator?

 

I believe a guy somewhere on youtube wrote in the comments that he was able to replace it without removing the alternator.

I was also on the fence, and considered replacing only the pulley, but ended up just replacing the whole alt due to age considerations.

UPD. Ok, he doesn't specifically say he did not remove the alt, but he kind of implies:
https://www.youtube.com/watch? v=wIc3g2e5y7E

 

AH HA!! That was it.
The new pulley solved the squealing noises.
I did have to pull the alternator out, but not too bad this time, 15 mins out, and 20 mins in.

 

COME ON!
I've spent like 2 hours to pull it out... Including the prep aka disconnecting the silencer and removing the belt etc.

 

BIG NOTE: For anyone attempting to remove the alternator. Please go ahead and change your alternator's voltage regulator while you have it off as well. It goes bad and causes the evil red light " ALTERNATOR VISIT WORKSHOP"