Alternator question: Paris Rhone and Bosch interchangeable?

Bob Prosser · 09-21-2010, 06:53 AM

Alternator question: Paris Rhone and Bosch interchangeable?

It's time to replace the alternator in my '88 911. It's a Paris Rhone unit (PN: 911 603 120 05).

My local Porsche parts guru says "Rebuilt Paris Rhone units are crap." He says get a new one or a rebuilt Bosch unit.

Hmm. Pelican Parts has a rebuilt Paris Rhone unit for $189. I called them to ask ... no complaints they know of ... so does anyone here have experience with a rebuilt Paris Rhone alternator?

If it's not up to par, does anyone know if a Bosch unit is directly interchangeable with the Paris Rhone, i.e., are the connections exactly the same? I'm getting conflicting answers. Some say I have to rewire the back ... something to do with the idiot light.

Thanks in advance for your answers.

304065 · 09-21-2010, 07:44 AM

Yes, the connections are identical. There are only B+, D- and D+/61 on the back, these are internally regulated alternators that do not use a DF wire or external reg.

Be extremely careful, disconnect the battery negative before working on the alternator, if the B+ shorts to ground you will have an 800 amp arc welder back there, could cause personal injury or property damage.

Targa Me · Targa Me's Garage

LOL, my Paris Rhone Alt needs rebuilding about every 40k miles. What i've done is bought a second unit so there's no down-time, i just swap them out.

Bob Prosser · 09-21-2010, 07:53 AM

Thanks for the info 304065. One thing: I think you meant to disconnect the battery's positive in this particular case, right?

Bob Prosser · 09-21-2010, 07:55 AM

Targa Me: so you are saying that they are crap, then? What is wearing out on them -- the bearings?

gtc · gtc's Garage

It's a crapshoot. I bought a rebuilt Bosch, and it went bad within a week. I believe my mechanic got me another Valeo, and all has been well since then.
According to my records, my car's alternators last about 75,000 miles. I guess I'm due for another one next year.

Bob Prosser · 09-21-2010, 09:48 AM

Man, I just don't get it. If the brushes, bearings and voltage regulator are replaced, why can't these reman units go the distance like the OE units? (180,000 miles in my case).

Targa Me · Targa Me's Garage

BP, it always seems like its the bearings that are failing.

304065 · 09-21-2010, 11:38 AM

Quote:

Originally Posted by Bob Prosser

Thanks for the info 304065. One thing: I think you meant to disconnect the battery's positive in this particular case, right?

No, the negative is what I meant. No ground from battery to car=no current path through the body or engine case back to the negative terminal of the battery = no closed circuit= no burn house down.

If you disconnect the positive you still have to worry about accidentally shorting to the positive terminal. If you drop a wrench on the positive and it hits the body, spark time. If you disconnect the negative and drop a wrench on the positive and it hits the body, nothing happens.

Bob Prosser · 02:40 PM

Got ya 304065 ... thanks ... well I pulled both terminals off yesterday for good measure. Plus when it comes to ignition parts, I have no idea what wires may still be hot, and only need to find a ground and ZAAAP.

FYI, I have found a place here in Oceanside Calif, who does a total rebuild of the existing unit for $165, including high quality bearings, etc. ... not the type that last for only 40K miles.

Richer Auto & Truck Electric -- (760) 757-1201

It'll be done in two days. If it's less than expected, I'll let you know, otherwise I'm a happy camper.