Blue Ocean

Have a listen here:
Pretty sure I'm dealing with bad alternator bearing.
Any way to know for sure before I order a new bearing and belts?
Hate to get into it and then find out I need more parts.

Thanks!

k722070

wow! shut that thing off. certainly don't stand near it.
look for evidence of fan blades hitting the shroud. if one of those blades brakes loose damage will occur.
I hope I am wrong.

anyway, outside of the cow bells, if the alternator bearing is going bad you should be able to feel it
by placing your hand on the fan shroud, the vibration will be obvious.
just don't do it if the blades are hitting the shroud.

motobri

LMAO at the thread title! Perfect.

ble2011

Its either the fan hub bearing or alternator bearings. Ether way, you probably want to just start taking it apart. You'll quickly find the issue. It's not too bad a job, I had to do it twice because my replacement alternator bearings failed within 3 months. I followed this write up with the exception, my fan hub just slid off/on the alternator shaft.
http://www.pcarworkshop.com/index.ph...or_Replacement

C4SJOHN

One of your fan blades is ready to go boom!

kjr914

Good advice above. Do NOT run the car any more. Your fan is dragging on the fan shroud and can explode sending chunks into the engine and rear deck lid. Remove and inspect.

It is slightly possible this is only a bad bearing (fan or alternator) that is allowing the belts to pull the fan down into the shroud (would be hitting only at the bottom of the fan shroud). BUT more likely is a bad fan that is about to chuck off a blade (look for cracked blades, and shroud damage other than at the bottom).

While you are in there, check the play in the alternator shaft (bearings bad?) and remove & inspect the voltage regulator on back of alternator:
1. are the regulator's carbon brushes worn? yes=new voltage reg
2. Are slip rings on alt shaft worn? yes= rebuild/replace alternator

P-daddy

Yep just went through this myself. I would remove all belts and spin the fan by hand to see where it's rubbing. Next, grab the alt shaft and wiggle fore/aft and side to side to feel for play in the shaft. How many miles on this alt/fan?

AOW162435

This. The fan & shroud are both magnesium. Magnesium does funny things when exposed to moisture. As these cars age, the factory coating on the fan fails due to debris getting sucked into the spinning blades or when worn bearings allow the fan blades to machine the bottom of the shroud.

Once the factory coating is compromised, humidity & other sources of moisture get to the magnesium and start the typical cycle of corrosion, cracks, split blade ends, etc.



Andreas

Blue Ocean

Ok gang, so what's the difference between these two:
http://www.sunsetporscheparts.com/po...?part_name=hub

http://www.ebay.com/itm/PORSCHE-964-...c71a44&vxp=mtr

And which is recommended?

AOW162435

The first one is the standard fan hub/bearing. If you're buying a new fan, the hub/bearing is already installed.

The second is a version of Porsche's 'RS' hub. This allows you to eliminate the alternator pulley & belt, and drive both the fan and the alternator with one belt. It simplifies matters and takes the fan hub's bearing out of the equation.

A minor downside is that this solution slightly under drives the alternator, resulting in less voltage at idle. And only at idle.

I installed the Clewett Engineering serpentine belt kit, which drives the alternator at a speed that's between stock and RS. Zero issues. None whatsoever.


Andreas

P-daddy

Blue- I went with the RS hub route. As mentioned this eliminates the alt belt and pulley. Now belt change is a snap. It's been about 2 months and I have no issues at all.

Blue Ocean

ok, hopefully last 2 questions.
- Do I have to remove the ac belt and if so, how?
- Where are you guys getting the new alternator brush / regulator assembly?
Sunset said they only sold after market.

thanks,

goofballdeluxe

Hey there! I know that cowbell sound!

I know I'm late to this party, but I heard that same sound in my car a while back. I thought it was the alternator bearings, but it turned out the fan had a nice crack in it. Replaced the fan and the shroud, and the only cowbell I hear now is when I'm Walken.

kjr914

If you still have your hands on that shroud, I know a certain Mr. Clean (posting above) that was looking for one in scrap condition.

Walken....hahahaha. My fav cowbell comes from Honky Tonk Women, not 993 fan shrouds.

goofballdeluxe

Keith, well, now you're a bit late to that party; I already gave it to a poor soul with a penchant for Shrouds of Stuttgart already.

Great. Now I have a Blue Oyster Cult earworm. Thanks guys!