Can I run a 55w alternator??

mb911 · mb911's Garage

Can I run a 55 watt alternator in place of my 75 w?? is it a bolt on?? And will it supply enough power?? Need to no ASAP

126coupe · 126coupe's Garage

I believe the 55w's housing is narrower. The 75w is wider therefore different housings

mb911 · mb911's Garage

Oh man go figure. I wish in wisconsin we had some one that could marchel parts a little faster.

Early_S_Man · 10-12-2004, 08:29 AM

Ben,

Does/did you car have the 840 Watt, or the 980 Watt Marchal alternator? If your existing alternator was/is an 840 Watt model ... you may be all set to use an older 770 Watt model, which was the same size. I repeat ... the 840 Watt and 770 Watt alternators are the same size!

In 1975 the housing was machined deeper, specifically to fit the [future] 980 Watt alternators, and the 840 Watt models had a 9.3 mm deep spacer 'ring' in the housing to make pulley fit correctly.

A search on eBay may net you a 980 Watt Marchal core or rebuilt model.

As you alluded to in your question/topic heading ... a 55 Amp/770 Watt Marchal/Motorola alternator might be fitted to your fan ... even if currently missing the spacer in the housing by fitting individual spacers [stacks of washers or tubing cut/filed to 9.3 mm height] to the back side on the studs between the housing and the alternator body.

mb911 · mb911's Garage

Warren I am not sure what I have other than the stock 81 marchel alt. Would the other work? If not does anybody have any leads on another

Lorenfb · 10-12-2004, 10:44 AM

If you're really serious about a 70 amp Marchel alt., call Tom Gould at Pelican.
He can probably get one for you. Avoid using the smaller 55 amp alt. in you car.
They are a very poor design and prone to failures in the diode plates.

Jdub · 10-12-2004, 12:26 PM

Can anyone identify the following alternator? From the label:

Valeo 14v 75amp A14 N 11 PORSCHE 911 603 120 04 J O

Many thanks,
John

73911guy · 10-12-2004, 01:55 PM

Early S Man is correct - the fan housing was made a little deeper as time went by but the part number cast into the housing PROBABLY was not changed - I've got one for a 55 amp Marchal and one for a 75 amp Marchal, they both have the same part number on the casting but they are different.

I've also got one 55 amp Marchal alternator, one 75 amp Paris-Rhone (ie Marchal / Motorola) (both functional units) and one 95 amp that won't fit any of the early housings that needs a VR that I haven't had time to put up for sale - if interested, send me an email at:
dasher-j@insightbb.com.

Thanks

Jim

Lorenfb · 10-12-2004, 11:14 PM

Can anyone identify the following alternator? From the label:
Valeo 14v 75amp A14 N 11 PORSCHE 911 603 120 04 J O

That alternator was the stock alt. that came on the '82 & '83 SCs.
It's the least reliable of all the Porsche alternators. Total junk!

mb911 · mb911's Garage

Thanks I think I have a rebuild coming this week. I hope its the right one. Its a rebuild from beck/arnley we will see. If that does not work 73guy we need to talk