Just recently, a low frequency loud ticking/clicking noise seems to be coming from the front left (passenger) engine compartment. The noise seems to be loudest near the alternator and gets much louder at higher RPM. I removed the drive belt and checked all the pollies, which seem to be fine. This is a 2004 CLK320 with 90k mi. Has anyone seem this problem? See the video from this link.http://www.youtube.com/watch?v=N5G-KL6RGGo

 

sounds like waterpump, have you had it changed? timing chain?
i would suspect power steering pump however that is usually
a high pitched rubbing sound

 

The water pump and timing chain are original. I don't expect the timing chain having problem at only 80k mi, I think it should last beyond 200k mi. I checked the water pump polly (with the belt removed) and it seems fine, it does not wobble and the bearing seems smooth.

 

its your alternator. mine sounded like that before it failed.

 

Thanks for the feedback. After reading your reply, I did some search online and in youtube, sure enough, this distinctive grinding noise is from the failing bearings of the alternator. Other people have posted some videos related to this problem in youtube. I'm going to use a section of the garden hose as a stethoscope to confirm that the noise is indeed from the alternator before buying a new/rebuilt one.

 

I changed the alternator on Sunday and it took 2 hrs. Originally, i thought it would take only 1 hr, which is the typical time on other cars. I have to say that this job is far more difficult than on other cars, such as BMW, Toyota or GMs.
There's very little room in the back of the alternator to work with, i got some cuts on my hands as a result of taking out the alternator.
Here's the procedure I would recommend + some tips & tricks. I didn't take pictures, but can take some later and post them.
1. Remove battery negative terminal.
2. Remove engine cover and vent duct on passenger side.
3. Remove drive belt: only one. Nut on tensioner is 17mm. Rotate counter-clockwise & remove belt. Draw a picture of the belt position before removing it; you'll need to refer to it when putting it back.
4.. Remove the two long mounting bolts (12mm I believe) holding the alternator. (There maybe 4 mounting bolts on some models, I don't know). Use a pry bar & pry the alternator loose.
5.. Flip the alternator facing down (pulley facing down). There's a plastic cap covering the 13mm nut. Remove that w/ a flat head screw driver. Remove the large positive wire by removing the 13mm nut. Unplug the wire harness.
6. Take the old alternator out: Some pipes and hoses are on the way, you'll need to remove some plastic clips holding down the hoses, and move (not disconnecting) the hoses out of the way.
7. The hardest part. Drop in the new alternator. Connect the wirehareness. Don't connect the positive wire yet. Now wiggle the top of the alternator onto the fitting slot; need some muscle to wiggle it in; insert the long bolt, it maynot smoothly slide into place -- just wiggle and push at the same time, you maynot be able to align the hole on the alterntor and the hole in the mounting plate, the trick is to wiggle the bolt and slightly wiggle the alternator at the same time and push the bolt in. Tighten the bolt 1/2 way. Now wiggle the bottom of the alternator into the bottom fitting position. Insert the 2nd bolt and wiggle both the bolt & the alternator at the same time until the bolt can slide into position. Now tighten both bolts.
8. Connect the positive wire on alternator & tighten the nut.
9. Put the drive belt back on.
10. Reconnect the battery terminal.
It took me 2 hrs to do the whole job. Next time, it won't take more than an hour.

 

Thanks for the info! Where did you purchase the alternator from?

 

Bought the rebuilt alternator from autohausaz.com for ~$186 + $110 core deposit. It's a Bosch rebuilt.

 

Do you remember if the alternator came with the pulley?

I noticed on their site it shows it without... Seems like some places have or don't have it... If it does have the pulley, I'm going to order from them.

Thanks,
-Nigel

 

Hey Nigel, the part number AL0787X that you were referring to in your emaildoes come with the pulley. The current pricing is $187.94 plus $108.00 refundable core deposit. Feel free to shoot me an email or call1-800-240-4620 if you need anything.

2005 Mercedes CLK320 Alternator