Testing an Alternator out of the car, yeh, it's out.... now what..... Options

[krk]

Folks,

Been following the P manual on the diagnosis front for the alternator in my /6. "Charging contol lamp does not extinguis shen speed increases".

Cause:
a ) earth short circuit in line D+/61 between alternator and regulator
b ) Regulator defective
c ) Exiting diodes are interupted

What I know thus far - swapped regulators with a known good one. No change.

So I'm down to a) or c).

a ) says "test with ohmmeter and repair if required". How do I do this? I have an "Equus 3000" (prolly a 20 yr old volt/ohm meter). I can find one end of the D+ line. Where is the other? (anyone btdt?)

c ) the p-manual gives formulas for using a "Bosch Alternator Tester". I don't have one of these (of course). Is diode testing something one can do with a boring ohm meter?

kim.

[hargray2]

(I THINK) diodes should read very low ohms, like 0, and should only conduct in one direction. A high ohm reading may indicate 'leaky' diodes which would not pass much current. remember to read in both directions.

[Drums66]

Kim, if you have a Kragen near by they are set up for testing Alternators and starters(free) (IMG:style_emoticons/default/wink.gif)

[krk]

Kim, if you have a Kragen near by they are set up for testing Alternators and starters(free) (IMG:style_emoticons/default/wink.gif)

cool. There has to be one near me!

kim.

[krk]

(I THINK) diodes should read very low ohms, like 0, and should only conduct in one direction. A high ohm reading may indicate 'leaky' diodes which would not pass much current. remember to read in both directions.

Thx. This dovetails with the manual's description of using their "alternator tester".

I'll poke at it later tonight (family duties about to call)

kim.

[hargray2]

let us know what you find out

[krk]

Alrighty then -- things are perhaps more interesting.

In reading the shop manual, they list the part number for the alternator as 901 603 110 00. The number on the alternator I pulled out is 901 106 101 5R. The cabling is slightly different as well. The manual looks like it has a wire cluster, and an individual wire to B+. The one I pulled out has a wire cluster, and two individual wires. B+ get's a black wire, D4 gets a red wire, and the cluster is called 0F (it looks like) and instead of being a three blade cluster, it is only a two blade cluster. (so it looks like perhaps one of the wires has become a separate wire in later versions of the alternator?)

So... anyone know anything about alternator numbers?

kim.

[krk]

fwiw, it looks like 901 106 101 5R (type 27) is some sort of standard 911 alternator. At least, that's what google seems to indicate.

kim.

[si2t3m]

Kim,

The 901 106 101 5R is in reference to the Fan Housing part number, not the alt.

As for the alternator, look on the back side of it. You should have a brand or part number for it. look for Marshal, Bosch, Valeo, Paris-Rhone or other brand name on it. This will get you somewhere.

Marc-André

[si2t3m]

Also, i think that at one point, Porsche decided to superced the alternators for Bosch units with integraded voltage regulators. I do know that there is a Technical bulletin regarding this.

I'd simply get the alternator rebuilt (BUSHINGS, diodes...) It should cost you around 100 or less.

Marc-André

[krk]

Also, i think that at one point, Porsche decided to superced the alternators for Bosch units with integraded voltage regulators. I do know that there is a Technical bulletin regarding this.

I'd simply get the alternator rebuilt (BUSHINGS, diodes...) It should cost you around 100 or less.

Marc-André

So I took Marc's advice --- hm, that's at least the second time on this project, way to go Marc! -- and took the alternator into an alternator shop. They tested it -- dead (burned out something that controls charging -- and they had a replacement. They even put it in the fan assembly for me. 129 bucks. (Auto Lectrics, Campbell)

Now if the weather will cooperate! (reassembly will be documented on the original thread)

kim.