VW MK4 Jetta issue

[RedManS4]

I know, I know, this forum is for Audis. I have an Audi S4, the car in question though is my girlfriends Mk4 Jetta 2.0L. I already have the post up in VWVortex however i find that Audizine has more knowledgable users, so I come to you. Heres my post from VWVortex:

So im trying to diagnose my girlfriends issue with her car. When she starts it, the car will make a very loud rattling sound, not really grinding, but like metal on metal contact. Sometimes the sound goes away, but when the car is cold it is a guarantee. The battery light is also on, which was not the case when the rattle first started. I first thought (and hoped) it was perhaps the serpentine belt tensioner as I researched that when it fails it can make a loud rattle sound.

Once replaced, the same issues occurred. So I went ahead and put the old one back on since it was not the issue. Note that the old one and new one both shared the same tension applied to the belt and the pulley was still smooth without issues.

Using a stethoscope to try to determine the location of the rattle a bit more precisely I found the noise to be coming more from the alternator. Weird because I recently replaced it within the last year. I went ahead and removed the tension from the belt and played with the alternator for a bit. The clutch felt good when i used a screw driver to hold the fan and tried to move the pulley. One direction moved with ease while the other direction refused to budge, perfectly normal as I researched. The thing that I noticed that I thought was unusual was the fact that the shaft of the alternator had some play (Video below).

The belt has plenty of tension on it so i do not believe that it is slipping on the alternator. I push the belt with the tensioner engaged and the tensioner does not budge.
I decided to measure the voltage coming off the alternator with the car running and it was at 10.95 which im pretty sure is very low for these cars.

Any advice or input would be appreciated.

[tar]

why didnt you post this in the s4 section then?

not like this is a motor b5 a4s get.

and yes that voltage is low should be 13.8 if i remember correctly.

[RedManS4]

why didnt you post this in the s4 section then?

not like this is a motor b5 a4s get.

and yes that voltage is low should be 13.8 if i remember correctly.

The A4 1.8t is more of a similar built engine to the 2.0 then the 2.7t is. Thanks for the info though, I went to autozone to check out a new alternator and noticed it does not have any shaft play, and all the staff agreed if there is any shaft play then the alternator is shot. Fortunately I do have a lifetime warrantee on it so it will be a cheap fix.

[RedManS4]

Fixed. It turned out to be the alternator, warrantee covered it.