polar964

Can you any of you folks shed some light on this. I have a 1993 C2. I have had the alternator checked and the rotor was 'shot'. It was either £170 for a new rotor or £193 for a recon with 12 mths warranty. Seeing how it wasn't the original alternator and that it had only lasted 14000 miles (4years ago by Porsche main dealer) thought i would be best with the recon'. However, the recon alternator puzzels me slightly.
It may be nothing but i'm meticulous, so just want to make sure everything is right and as it should be. There is a sleeve which slides over the shaft before the dual bearing is located. The sleeve pushes up against a larger ring (30mm diameter) which protrudes from the alternator body. This ring protrudes approximately 2mm further than on the original. The question is, is this critical to the position of the pulleys on the shaft after assembly. Technically they will be out of line by 2mm with the pulleys on the crankcase (assuming they are re-assembled exactly as they came off). The current sleeve length is 24mm long, logic says this should now be 22mm. Is this correct?
I am also assumeing that the one i am replacing was right !

Would very much appreciate some advice. Thanks
Paul

drisin80

i don't directly know the answer but have a couple of thoughts. did you check to see if the shaft length is identical on each of the alternators-- where the pulleys are located. logic dictates that this is the most important measurement--as the adjustment of the belt tension is accomplished by use of the spacers. if this is the case--perhaps the 2mm can be accouted for by a slight difference in the alternator casing, and the way that it is seated into the fan housing???? if it seats slightly deeper in the housing this could account for the discrepency. just a thought---tom

mojorizing

The "ring" might not be fully seated down shaft. I would fit up the stack ( bearing hub, spacers sheaves, etc) while it's removed, torque down on the nut, then disassemble, and then check again the amount the ring protrudes. Let us know what you find.

later, Kevin

colo964

check the part number. My OEM was 911-603-155 for a pre 1991 or so. The bronze sleeve did stick out about 2mm more. The new refurbished one I got was 964-603-156 AX; it required about a 4 mm spacer (split ring lock washer) to make it align with my pulleys. Sounds like you got a -155 when you need a -156. May be grind the sleeve by 2-3 mm.

BTW: an alternator should last far, far, far more than 14000 miles unless you get metal shavings or sand in the bearings or your alignment is off, or belt was too tight.

polar964

thanks for replying guys.

From the photo, the 30mm boss which the spacer is up against is exactly as mine is on the reconditioned alternator. On the one which it replaced, the boss didn't protrude as far (2mm less in fact). What i intend to do now is re-assemble and check pulley alignment with the ones on the crankcase. Having seen your photo i feel less concerned.
Cheers
Paul

Drive your passion drive a Porsche ... better still drive a 964 ....

mojorizing

Polar,
That photo came from http://p-car.com/
from the write up on how to change your alternator.

Verify the part #'s as colo964 sugeests, that could explain it.

polar964

Difficult to check the part number as i obtained the recon alternator from an independant alternator and starter specialits who was recommended and used by my indepandant well known porsche garage. The alternator that was substituted was a recon unit in November 2002 at a porsche main dealership with the part number 964-603.156.AX. Although they have a porsche part number they are made by companys like Bosch.

On the photo, althought the boss is the same, the shaft shows an additional piece after the threaded end which mine does not. Not that this end will effect the position of the pulleys. Wouldn't you think they would just stick to one design. I'm sure they do this just to make things more complicated and to put us guys off from having a go ourselves, when we are just as capable.

The cooling fan is sparkling and the housing has been refurbed, just got to put the thing back together and get back on the road ....

Thanks again for replying really appreciate the advice
Paul

mojorizing

The end of that particular alternator had been stripped out and a new allen head socket was Tig'd on as a repair.

You polished or painted your fan?

polar964

that explains it then: Going to re-assemble tomorrow. Will take a photo to show you guys when its done.

Polished the fan ... wanted to keep the colour original. With a clean and polish it came up like new. Thought i would try this first and if no good would have it refurbished. The housing i cleaned to remove some oxidation which had occured over he years, then sprayed with high temp engine enamel matt black. Should all look the buisness when put together.

Will keep you posted ... thanks for replying

Paul

John Boggiano

Sounding good - fingers crossed for next weekend.

polar964

Well folks after all the advice and support received over the past couple of weeks i would like to say a big thanks to all those who responed to my call ! , cus this afternoon the key went in the ignition all the warning lights came on, including the altenator/battery light, then with a flick of the wrist the car fired up ..... absolute fantastic..... what a sound.... music to my ears ... oh and the altenator/battery light went out !!! just as it should . Checked the voltage across battery, everything charging fine. There's no sound quite like a 911. Thanks again and here's a photo the the job complete with polished fan and refurb housing. Unfortunately yer can't see the alternator but take it from me it looked just fine before the fan went on.
Cheers Paul