Nicole

Jus found an old email from A German 928 owner. He has an 89 and says the pulley has been changed from engine number M82.42 onwards.

Here are the bearings he put into the alternator of his 89 (purchased through BOSCH):
(NSK) 6201DUS 208 CG14B
(NACHI) 6303NSE2 F3 60 C/14 LI

The alternator originally had the following:
(NTN) 6201LUA CS20
(***) 565233 S 176

He paid about $20 for both bearings. He did not write anything about brushes or the regulator.

When I was in Germany last time I got a ride in his S4 with new bearings in all moving parts on the front of the engine. Despite lots of kms on the odo, this engine sounded as smooth as the 23,400 km GTS that was there also.

Bill Ball

Yep, those are the same bearings. We will use your current pulley. I'n not sure about your fan, but we can probably use that as well.

The Eagle Electrics are Bosch alternators rebuilt by them. But I gather you are interested in one rebuilt by Bosch.

Lorenfb

"Oncce the pulley is off, yoy can split the unit and gain access to both bearings. The brushes are pretty obvious there in the back. Clean everything of course before you reassemble. Whole job takes less than an hour even if you drag your feet and clean everything to new appearances."
- dr bob -

How about "turning" the slips rings on a lathe or testing the regulator for proper voltage & Vsat?

For those that don't want to find bearings, brushes, & a possible regulator replacement or visit
a machine shop, call 928 Int'l as they have rebuilt units.

dr bob

Loren:

Turning the slip rings on a lathe is a great idea if you have a lathe and know your limitations with the amount of copper on the rings. Most folks fall out of both qualifications. If the rings are seriously grooved, it's time for another alternator for the commoners. If they are just slightly discolored, you can make yourself feel better by using a Scotch-Brite pad to brighten the metal a bit.

I think I covered the voltage regulator operation in the "If you are making OK charging power now, no need to replace the regulator though." sentence in my previous post. Voltage regulators and diodes are not 'wearing' parts of the alternator, and will in fact last forever if they aren't abused electrically or mechanically/thermally.

Nicole posted about a little bearing noise as her problem, looking at ways to avoid spending whole-rebuild dollars to cure that problem. In my limited experience I've found that replacing the brushes is a safe and inexpensive WYAIT action, since they are the only other wearing part after the bearings.


Nicole--

The bearings, per your German owner's numbers, are commonly available at better parts houses. Look for 6201 and 6303 bearings with the same seals and shields as you have now. Try to find name-brans bearings if you can, although that isn't as much of a guarantee of quality as it used to be. Many top manufacturers buy their stock/commodity sizes from the lowest-cost suppliers anyway, and just put them in their own boxes.

Some import parts houses will have the brushes and bearings in stock too. The brushes are not unique to the 928 I'm sure.

Lorenfb

"Turning the slip rings on a lathe is a great idea if you have a lathe and know your limitations with the amount of copper on the rings. Most folks fall out of both qualifications. If the rings are seriously grooved, it's time for another alternator for the commoners."

Most/all alternators with > 50K miles require that the slip rings be turned or replaced. If this is NOT
done the new brushes don't "seat-in" properly or may "bounce" at high RPMs, resulting in adequate
field current. Why do a Mickey Mouse job which may require a "real" rebuild in the end?

"In my limited experience I've found that replacing the brushes is a safe and inexpensive WYAIT action, since they are the only other wearing part after the bearings."

And the copper slip rings!

Bill Ball

I found one place that listed the copper slip rings as a part for sale as a separate part, but forgot to bookmark it. Wagner does not list it and other places just sell it on the rotor. It may not be sold separately. I doubt we are going to do anything but make sure it is clean and ungrooved.

Bill Ball

Maybe it's one of these, but it doesn't appear so:
http://www.alternatorsparts.com/products.htm#1

Nicole's alternator is working fine, so what we are doing is similar to replacing a noisy AC clutch pulley bearing instead of the getting a rebuilt AC compressor. But we'll do the other accessible wear parts while we have it off.

dr bob

Bill--

Be sure to do all the stuff that Loren says. His knowledge and experience on this stuff is obviously a lot more substatntial than yours and mine combined.

Bob

Note to self: Figure out how to make the 'ignore' feature work for LorenFB posts to this forum...

peanut

something to bear in mind whenever fitting new belts. The new belt is going to be a lot tighter than the original which will probably have stretched over time. The increased tension will put a sudden additional strain on the waterpump bearing which could force an early failure. Mine started to fail within 1000 miles after fitting a new belt

Bill Ball

peanut:

Not sure I undestand. You must be talking about the timing belt (TB), as the alternator belt has nothing to do with the water pump (WP). Either way, these belts are adjustable. The TB tension should be checked every 15K miles, and the difference between the lowest and highest acceptable TB tension is not so great as it should cause a good WP bearing to suddenly give out. Seems coincidental to me. Most of us change the WP with the TB anyway.

BC

http://cgi.ebay.com/ebaymotors/PORSC...QQcmdZViewItem

Why not just get this?

peanut

I was refering to replacement of any belts. I would be extremly surprised if 1 person in a thousand 928 owners actually checked their belts every 15k miles ?

Here in the UK we are not so quick to replace waterpumps when changing belts. Cheapest available W Pumps here cost $650 + fitting and we invariably need to helicoil all the stud holes as well on early 928's so you can expect $1000 for a waterpump replacement and double that at a Porsche dealership

Nicole

OK, since the car is going to be aligned at DEVEK on Thursday, and the bellypan is already off, I decided to just have them plug in a BOSCH rebuilt alternator while it's on the rack.

This way, I'm more comfortable to have the car ready before next Sunday's fun drive. I would really hate to get stranded in the middle of nowhere with a seized alternator...

It would have been interesting to do the rebuild, though, simply for educational purposes.

BC

Have fun with your 400 dollar alternator...plus 100 dollars an hour for the two bolts its held on with.