Whirling sound - 96 C220 - PeachParts Mercedes-Benz Forum

tobybul · #1 09-22-2008, 09:28 PM

After I put in a reman alternator (from Autozone) I hear a high pitch, whirling sound which I believe is coming from the alternator area (I put on a stetoscope and poked around). I returned this alternator and got another one and its doing the same thing. Now I'm wondering if its the alt or something else.

But my stetoscope tells me it is coming from the alternator area. Could it be that the AZ remans are not done well? Anyone have a similar experience?

mpolli · #2 09-22-2008, 09:43 PM

I usually find the stethescope is too loud for bearings. I like to use a long stick and hold one end to my ear. It could be you over tightened the tension of the belt. This is a common problem for beginning mechanics. I am not saying you are a beginner but if you are just make sure you did not tighten it too much. I used to do this until I burned out some bearings and someone told be better. Anyway, you should be able to track down where the noise is coming from. Could be the alternator bearing or some other bearing such as the tensioner pulley. As far as remans, they are often lousy, so I try to buy the best I can find even though it is not the cheapest. A cheap one with a warranty is not very good. It just means if this junky one breaks you can take it off and we will give you the next junky one.

tobybul · #3 09-23-2008, 08:37 AM

Quote:

Originally Posted by mpolli

I usually find the stethescope is too loud for bearings. I like to use a long stick and hold one end to my ear. It could be you over tightened the tension of the belt. This is a common problem for beginning mechanics. I am not saying you are a beginner but if you are just make sure you did not tighten it too much. I used to do this until I burned out some bearings and someone told be better. Anyway, you should be able to track down where the noise is coming from. Could be the alternator bearing or some other bearing such as the tensioner pulley. As far as remans, they are often lousy, so I try to buy the best I can find even though it is not the cheapest. A cheap one with a warranty is not very good. It just means if this junky one breaks you can take it off and we will give you the next junky one.

Thanks for the tips. Actually, the C220 has a self adjusting, spring loaded tensioner. So, aside from pulling it back to loosen the belt, I did not do anything else. I'll try the stick approach. I did put the stets on the tensioner pulley but no noise. However, it was more pronounced around the alternator.

As I said, the noise was not there with the old Bosch alternator.

Ethan · #4 09-23-2008, 10:43 AM

who took the pulley off the old alternator and placed it on the remanufactured Autozone unit?

tobybul · #5 09-23-2008, 05:49 PM

Quote:

Originally Posted by Ethan

who took the pulley off the old alternator and placed it on the remanufactured Autozone unit?

I did...

I made sure it was back on like it was originally. Theres a washer/spacer that does in b4 the pulley and bolt.... I used my impact wrench at lowest setting to tighten the bolt while holding on to the pulley.

I also tried the stick method but used a long screwdriver instead to find the noise. Definitely coming from the alternator.

I hope you are on to something with the pulley installation. I can't imagine 2 alternators doing the same thing.

mpolli · #6 09-23-2008, 06:52 PM

Screwdriver works good too. Just make sure it is a long one! Don't want to get your head anywhere near any spinning parts...

tobybul · #7 05-04-2010, 11:11 AM

just a follow up on this... i eventually returned the AZ alts and got a bosch reman online which has been in the car for about 2 yrs now. the online reman did not have the noise.

I did contact the AZ supplier/remanufacturer out of CA and told them of the problem. this was after I filled out an online feedback form in the AZ site. they were pretty good at getting back to me to give their supplier info.