993 - Alternator Replacement

From pcarworkshop

Alternator brush / regulator assembly replacement and RS pulley hub installation

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

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.

3. Loosen and remove fan housing strap

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

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

6. Loosen and remove fasteners for all three wires – it helps to use a magnet stick to capture small fasteners.

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

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

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.

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

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

Image of new vs. old brushes

14. The alternator shaft was rusty, a little Scotch-brite cleaned it right up. This allowed the RS hub to slide-on without interference

15. Before installing the RS hub into the fan, I applied a small film of Copaslip antiseize for good measure.

16. Reassembly is basically the reverse of removal with the exception of only having to install and shim to set tension of one belt.

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!

Original Article Credit : Chris Walrod

geolab "It was very frustrating for me to open the hood of any 993 and see the alternator shaft threads dead. This socket where the Porsche tool holds the shaft, is very soft iron, if you tap on it with a hammer to remove fan because the rubber mallet did no effect, the socket tip end of the shaft will melt and open like a flower. There is another safe and effortless way to remove fan and hub from shaft without jaw puller or extra tools or zero tapping. Take one of the three hex bolts that hold the pulleys to fan hub in picture 2, and go to your local store and purchase 3 x the same bolt but double the length (about 4 inches long bolts), make sure they are threaded up till the head of the bolt. Hold fan with alternator upright fan facing up. look in the bolt holes in hub and tilt the alternator from fan so that there is metal from the alternator face front, behind these three holes. Now introduce the three long bolts you got from the store by hand until they block. Now tighten each bolt one full turn before passing to the next bolt. While tightening in a circle, the alternator shaft will start sinking in the hub. The bolts will push away the pulley from alternator until the shaft is out, voila !"