alternator question

[mb911]

I have a couple quick questions about 911 alts.

1st what would cause one to over charge even thought the regulator is brand new?

2nd is there a difference between marchvel and bosch housings that is fan housings? If so how do you convert them to the more availble bosch unit?

Thanks
Ben
77 911 3.0

[pwd72s]

"77 911 3.0?" You put an SC engine in your '77? Does your 3.0 contain an alternator with an internal V. regulator? If so, this could be your problem...No external V. regulator needed, or desired, if that's the case...

[mb911]

No its my 914-6 that the problem is with. The engine is from a 74 911s and has an external regulator. The thing boiled my battery today. I would like to figure out what is going on with it and fix it as here in wisconsin we only have about 3 weeks of driving weather. (just kidding) but really if any one knows the story behind converting to the bosch style alt using the old fan housings that would be great. As far as my alt I believe it is the ones that have the replacable brushes on it. I have never looked real close at it and am not looking forward to it in a 914-6. My 911 would be cake.
Ben

[Lorenfb]

There is a possibility that the D+ and the DF wires are shorted causing
the alt. to charge to max. Another cause can be the field diodes being
open making the regulator think that more output is necessary.

Good luck
Loren
Systemsc.com

[mb911]

Great looks like I need to get started in removing it. Should be great fun
ben

[Lorenfb]

Don't remove the alt. until you check everything out completely.
If it still charges with reg. unplugged, then the wires are shorted.
If the diodes are bad, it won't charge w/o reg.

Good luck
Loren

[mb911]

Ok I think I found the problem? I asume that if the DF lead is not going to anything than the regulator won't work? Does this seem correct?

Thanks
Ben

[Lorenfb]

The DF and the D+ both go to the regulator for the alt. to work properly.

Good Luck
Loren

[mb911]

The DF was flapping in the breeze not conected to anything. Just think I had just replaced the regulator because it was over charging. Guess I wasted $60 bucks. I will reconnect and see what happens. I am going to also have the alt checked out so that I am sure. I see the marchel alts are big bucks and not many people can get parts. I am so lucky I have one in my 911 also.

Ben

[RoninLB]

Originally posted by mb911
I see the marchel alts are big bucks and not many people can get parts. I am so lucky I have one in my 911 also.

Ben

I up-graded to a Valeo internal regulator.. it's a good unit.......Ron

[mb911]

Are those direct bolt ins? How much are they? I can't see spending $500 on an alt.

Thanks
Ben

[Lorenfb]

You wasted your money! The Paris-Rhone is the worst alt. made for
Porsche. Wait until it begins to over-charge. I wish I could easily
replace my '88 3.2 with an old 3.0 Porsche 70A Marchal alt.

An internal regulator is just not good when you have it near an
air cooled engine head.

It'll probably be OK as long as you drive the car in a Chicago
winter. There have been many posts discussing alt. problems
on this board and Rennlist. Many Porsche owners have mentioned
the over-charging problems. A 914-6 is a great car to remove
an alt. from.

Good Luck
Loren
Systemsc.com

[SteveF_911]

Try K3 site. They make replacements alternators

http://www.k3.com.au/index.php?page_id=2

They can let you know what type you need

[RoninLB]

Originally posted by mb911

Are those direct bolt ins? How much are they? I can't see spending $500 on an alt.

yeah Ben... it's a direct bolt in.. after you trim a little of thr air channel gizmo.. that's if your going from external to internal VR.. I can't tell what your car is?.. my unit was about $300. but some of the later years was about $400.. maybe it's higher amps/not sure.

Loren makes a good point about the internal VR getting heated.. I don't have hard info on that, but I ordered a replacement VR when I ordered the new Valeo that's kept on board full time.. I think it was a logical assumption a few years ago, when I ordered it, that PC boards and heat is NG.. I think la la land guys would have a clearer pic on toasted VRs than me. S Calif. traffic is so much fun for a 911. and there is a somewhat informative book around that says the later alt. is good for 40k miles.. maybe that has to do with the internal VR/don't know. and I installed a volt gauge for security..

and if your going from external to internal VR.. the Valeo didn't require the "G" lite/alt. lite mod.. it was a simple plug and play.. and you get to by-pass the in line external VR "noise supressor", which you can do with the external VR anyway.. but most guys don't even consider that..

what I always liked about the external VR is that I could always "full field" it.. I don't know how to do that on the internal VR?

[Lorenfb]

Yes, you can't really do any testing with an internal reg. alt.
They work or you pull them out. Fun isn't it.

Good Luck
Loren
'88 3.2