chris walrod

Alternator brush / regulator assembly replacement and RS pulley hub installation

There is an alternator R&R DIY write-up on p-car.com. I thought to include images of my R&R as well.

I have all service and repair records since the car was new, but don’t see any indication of alternator replacement. So with almost 99k on the clock, I thought, as a preventive measure, to replace the brush / regulator assembly. While I was there, I thought an RS pulley install was needed

**Disconnect battery first**

1. Remove the alternator belt pulley
http://img169.imageshack.us/img169/9...ture001lm3.jpg

2. Remove three socket head bolts and remove fan belt and pulley -- * use quality allen drivers for these bolts as they are shallow and soft – be deliberate in cracking these loose using pressure to keep the driver straight to prevent slipping and eventually rounding off the allen.
http://img329.imageshack.us/img329/5...ture002qv4.jpg

3. Loosen and remove fan housing strap
http://img155.imageshack.us/img155/7...ture003xo1.jpg

4. Loosen, but don’t remove, three hex headed bolts that secure the rubber/plastic ducting. This will gain you access to the back of the alternator
http://img169.imageshack.us/img169/2...ture004lu3.jpg

5. Tilt the fan housing assembly towards you and remove four Nylock nuts. This will enable you to remove the black plastic domed cover exposing three electrical connections
http://img329.imageshack.us/img329/8...ture006sa1.jpg

6. Loosen and remove fasteners for all three wires – it helps to use a magnet stick to capture small fasteners.
http://img169.imageshack.us/img169/4...ture009dv2.jpg

http://img206.imageshack.us/img206/6...ture011fx7.jpg

http://img206.imageshack.us/img206/6...ture015ws8.jpg

7. Remove alternator / fan housing assembly from the car.
8. Remove the alternator from the fan housing *note: the fan will still be attached to the alternator
9. Normally, the fan can be placed onto wood blocks for support as one taps on the alternator shaft, pressing it out of the fan *note: use a SOFT hammer or a punch with a steel hammer taking extreme care not to damage shaft splines or threads – also place fan –hub- onto the wood blocks, not resting the fan blades on the wood blocks like pictured – for some reason my image showing this did not turn out

Since I was lucky and my fan was stuck on the alternator shaft, this, in addition to installing an RS hub, I used a large aluminum punch to tap out the fan mounting hub from the fan – see arrows pointing to where to locate punch

This was a good time to take a break and pressure wash my fan and housing
http://img206.imageshack.us/img206/2...ture021vp3.jpg

10. Once the fan was off its hub, I used a three jaw puller with aluminum sheet to protect the end of the alternator shaft – it came off easily
http://img206.imageshack.us/img206/3...ture025nq9.jpg
11. Remove small fan from the forward alternator shaft to gain access to the brush / regulator assy. I used an impact gun set on the lowest setting and it came right off.
http://img329.imageshack.us/img329/3...ture029uq2.jpg

12. Remove two Phillips headed screws that retain the brush / regulator assembly located on the backside of the alternator – (I don’t have an image) Before installing the new brush assembly, clean all connections with fine sandpaper including the alternator ground wire connection
http://img329.imageshack.us/img329/4...ture031ia1.jpg

http://img218.imageshack.us/img218/5...ture033qs3.jpg

http://img329.imageshack.us/img329/5...ture032ye1.jpg

13. Install new brush / regulator assembly – the brushes are spring loaded, so you’ll need to hold it into place while you start one of the fasteners – use a little blue Loctite (#242) on the threads
http://img218.imageshack.us/img218/8...ture035rq6.jpg

Image of new vs. old brushes
http://img329.imageshack.us/img329/8...ture030xd3.jpg

14. The alternator shaft was rusty, a little Scotch-brite cleaned it right up. This allowed the RS hub to slide-on without interference
http://img206.imageshack.us/img206/2...ture039rk5.jpg

http://img218.imageshack.us/img218/9...ture041in2.jpg

15. Before installing the RS hub into the fan, I applied a small film of Copaslip antiseize for good measure.
http://img206.imageshack.us/img206/3...ture045ot0.jpg

16. Reassembly is basically the reverse of removal with the exception of only having to install and shim to set tension of one belt.
http://img218.imageshack.us/img218/3...ture048tu2.jpg


Go for a short drive and return to recheck the belt tension and verify the shaft nut and the three pulley Nylock nuts are tight.

While not expecting to notice a difference, I do. Engine seems a little quicker to rev and more responsive. I was surprised!

Garth S

Nicely done!
I recently went through this with an engine on a dolly - much better access : however, as a precaution, I will also pull the alt & fan from the car .... mostly to see what garbage has collected to block the jug fins ( found chunks of v-belts over the fins of the spare, and the had PO replaced several belts - parts of which were beneath the crank pulley ..... think some more bits will be found inside.)
This would be a good time to refresh the brushes - thanks for the prompt. Normally, I'd just solder new brushes into the reg holder - is this a standard Bosch bush assembly, or one unique to the 993?

chris walrod

Garth, I am not certain if its unique to the 964/993 alternators - my guess would be -no-, but not certain.

One thing that was nice to do is take some time with a flashlight to peek at the top of the engine looking for rats nests, garbage etc. Luckily mine was dry as a popcorn fart

epj993

Nice work Chris! I guess I'll add this to my to-do list...

tj90

Thanks for the DIY! - we need to add to p-car.com if its not discussed there already.

Jeff96-993

It should also be added to the DIY page here on Rennlist!

Lorenfb

"I have all service and repair records since the car was new, but don’t see any indication of alternator replacement. So with almost 99k on the clock, I thought, as a preventive measure, to replace the brush / regulator assembly."

The bearings should have been replaced given the mileage, i.e. 99K, especially with extra long
shaft on the 964/993 alternator which provides an extra front bearing load, since the alternator
was out.

chris walrod

Yes Loren, that thought went through my mind. Despite the bearings feeling like new, I know they arent and perhaps another project when the engine it out in a few weeks for the LWF.

JasonAndreas

Chris,
Do you happen to have the Bosch part number for the voltage regulator? Directly from Porsche this thing has an MSRP of $173.05!

Is there a minimum ABEC rating we should use when replacing the bearings?

chris walrod

Part number on the Bosch box is 30 091 -- Not sure if that is the actual Bosch part number or not -- about $85 on eBay...

amfp

Thanks much Chris. Well done. This is one DYI, I will keep on file for the future.

Jascha-M

Pelican Parts sells these for $75.00 and the Bosch number is 1-197-311-040 (as I can best tell from the pic)

Porsche No. is 928-603-142-00

cbracerx

How about the part number for the RS Pulley? That seems like a near term purchase...

chris walrod

Sorry, I dont have that part number handy.. I am sure Sunset or Gert would know exactly what you are referring to. Here it is from Carnewal

cbracerx

This is it - 993-106-051-80