83 Porsche 911SC Alternator Problems

[logdudeslc]

A little help please. I just finished the top end rebuild on my 83 911 SC and still having trouble with alternator diode failure. This is the fourth alternator I’ve had rebuilt with diode problems. I had it bench tested before putting it back in and it was producing 71 amps. I only got 210 miles on it before failure. It’s a Paris Rohne and I think it has an internal voltage regulator. It happens when outdoor temps get in the 90s. All of the local shops are telling there is no longer a Bosh replacement but it looks like our host has one available. Any suggestions on where to go from here? I don’t want to keep spending on the same problem if there is a better solution.
Thanks
Dave

[Joe Bob]

Not sure but going with a different alternator requires different back spacing.

Who is doing the rebuilding? Most local shops warranty their repairs.

Have you considered going with an external VR? My euro 83 had one.

[logdudeslc]

The first three or four rebuilds were covered by warranty but the car has been garaged for five or six years and 210 miles so this one is on me. They only cost me a tow job and a long walk. I knew it had been a problem in the past so had it bench tested before installation. Would like to take the car to Jackson Hole or Vegas and just don’t trust the alternator and don’t want to through money down the same hole.

[na2ub]

With that failure rate, I would be tempted to get one from my local NAPA. They have reproductions for about $150. However, I do believe Pelican sells units other than Paris Rhone. A lot of them are rebuilts.

[wrxtremest]

I would not recommend the cheap napa/autozone versions. The cheap-ass voltage regulator started to fail as soon as my car reached full operating temp.

[kiwiokie]

Did they install a new VR when your alternator was rebuilt?

[wrxtremest]

It appeared as new.
Upon close inspection, one of the leads coming out of the regulator was not routed correctly through a hole. Consequently, it was badly pinched and I assume slightly broken.

[kiwiokie]

Sorry wrxtremest should have been more clear - question was for original poster who is on his 4th rebuilt alternator. In my 928 owning days I remember a guy had a similar saga with an alternator and it turned out the shop was removing the VR, rebuilding the alternator then installing the old VR again. Just a thought.

[47silver]

i was having alternator problems a couple of years ago, what i found was the wiring to the fresh air fan was shorted and causing alternators to burn out diodes (2 alternators)
check out all of the wiring