daveo90s4

Check crank end play. Is the front face of the flywheel touching any bolt heads at rear of block? Was on a friend's S4. Engine eventually seized. Thrust bearing was wafer thin - down to the hard steel backing. Hope this is not the problem for you.

kevin2012

Today, I took out the fan and tried to listen all the moving parts of the engine. I guess that I had found out the main source of the noise. (I think that every moving part is contributing some kind of noise. Whenever anything moves, it will generate noise). When I spray some WD40 into the alternator fan and the air duct of the alternator,; the noise got smaller. It still has the noise but a bit quieter.

Can the alternator be serviced or rebuilt? Or I have to buy a new one?
Thanks.

Schocki

It is possible to overhaul the alternator but you need a shop press to do it. There are specialized shops or call Roger from 928sRus...

jcorenman

Kevin, the best check would be to run the engine without the alternator belt? Have you done that? You removed the other belts, but from your videos it looks like you carefully worked around the alternator belt. The engine will run fine (for a while) with the alternator belt off, and is the simplest way (along with a stethoscope) to confirm the source of the noise.

The Bosch alternators can be easily rebuilt, but as Schocki mentioned you need a press or a puller, and a bearing-splitter to get to the bearings. The brushes also probably need replacing, those are part of the regulator and come out from the back. If the slip-rings are badly worn they can also be replaced, but that gets more involved.

Any alternator shop can do all of this easily, also 928 International (a long-time sponsor here) has rebuild's in stock. Roger may also stock them, but it is hard to tell from the website. [Yes, I know, you need to call... but seriously, it's 2013 already].

kevin2012

I had tried to get the alternator belt off but I couldn't get the adjusting nut off. it is just so damx tight and I am afraid that I will round the nut. I will need to ask my mechanic to change all the accessories belts and see if he can help me to have the alternator rebulit. Thks.

jcorenman

You said that and I missed it, sorry. There is not much room to get a wrench on the nut on the back of the adjuster, but you can remove the 8mm adjuster-bolt from the front side and then get a big wrench on that. You still need to counter-hold it from the back but you can apply most of the force from the front side, once the adjuster-bolt is removed. And don't forget to loosen the mounting bolt at the top of the alternator, once the bottom is loose.



And yes, your mechanic will certainly have a line on a good alternator shop.

kevin2012

Thanks, I see your point and will try again. My adjustment nuts are 13 mm and the locking nut is 17mm.

andy-gts

Soooo what happened , was it thrust bearing , or alternator?????

The Fixer

Must be the alternator then. That is a metal on metal noise, not a belt squeal noise. Good luck with it.
Matt

Mrmerlin

since the only belt you didnt remove was the alternator belt,
then the odds are pretty high that it has a failed bearing,
eventually the bearing will get hot enough to cause the races to start spinning in the their bores,
thus destroying the alternator housing, if thats the problem

kevin2012

Well, I had ordered all the accessories belts and will install them and see. Actually, I did remove the alternator belt and turned the pulley by hand, it turned smoothly and not much free play. However, when I put the old belt back and after tensioned the belt, the noise changed to quieter. So I look forward the result after I have time to change all the accessories belts.

Mrmerlin

did you run the engine with the alternator belt off as well as all of the others?
was there still a noise?

if with all of the belts off there is still a noise then you have to open the timing cover up to inspect the belt run, simply removing the top cam cover isnt sufficient

kevin2012

Yes, I did start the engine with all belts removed, the noise was gone. What a relief!
I am quite sure that it is alternator related. Either the bearing or the alternator's belt.

Mrmerlin

From the alternator then its a bearing,
you should remove the alternator and have the bearings replaced,
its not really too much of a job you need a small puller to remove the bearings, most rebuilders can do this
Only Caveat is how long the bearings have been grinding away and if they caused any race damage to the housing

joemqn

I have the pronounced squeaking pulley sound, as well. And it does sound like a nest of mice on crack. When the engine started to get hot and above the halfway point point on the temp gauge I got it home in a couple of blocks and haven't driven it since. The car has always run perfectly cool in the 15 months and approximately 2500 miles that I have had it.

I do have what I think is coolant/water leakage but it is not below the water pump near the front of the engine. The leakage is on the passenger side in the red area on my image upload. Basically underneath where the coolant fill tank is, and spread out. The leakage is mostly odorless and clearish, although it does smell a bit dank, like you would expect radiator water to smell.

I am hoping it's not the water pump, but fearing the worst. Any chance it could be as simple as the thermostat? By the way, the car was running fine as this all occurred. I haven't had a chance to get it to my mechanic yet. Any ideas or suggestions are much appreciated.