gpower

I have a 1982 911SC with a faulty alternator(I believe). Is the Bosch AL400X a direct replacement for the original Paris Rhone unit with integrated regulator. Thanks

joey c

i'm pretty sure its the paris rhone,but pelican parts will tell you.....just checked over at pelican,not really sure but for some reason i think its the rhone..j

Lorenfb

"Is the Bosch AL400X a direct replacement for the original Paris Rhone unit with integrated regulator."

Bosch never made a 911 alternator for the years '82 thru '89 for the SC or 3.2.

der Mond

I have a K3 alternator made in Australia with Bosch parts.

http://www.k3.com.au/

It is available from Pelican or Aase. It is expensive, but has a diode that may, if it works right, prevent the overcharging tragedy. 20K trouble-free miles thus far. I also recommend getting the best battery you can, since many issues result from low battery voltage. I have an Optima Red Top. With that one you just need to use an external charger to recharge it if you run it down by mistake, since it requires a lot of juice in that state.

Lorenfb

"but has a diode that may, if it works right, prevent the overcharging tragedy."

Totally ridiculous!!!!!!!!!!! When vendors make statements like that, the credibility of the
overall alt. design becomes questionable, but what do you expect from an aftermarket
product marketing?

That alt. puts out 90+ amps and there's NO diode (tranisent, zener or whatever) capable
of limiting the ouput when the regulator fails. The alt. being sold is the basic OLD Bosch design.

The original 3.2 90 amp alt. with the updated regulator is adequate and reliable!

der Mond

Loren,
My naivete in these matters is clearly visible.
Please explain this so a 5th grader can get it.
Would my alternator diode circuit not at least cause the dashboard warning light to come on if the regulator fails?
My understanding is that the overcharging scourge results from the driver not knowing the regulator has failed until he smells the battery cooking.
Can you tell me exactly what is the original 3.2 90 amp alternator, where it is available and how one can prevent cooking one's battery prematurely? Is there a recommended number of miles to drive the original alternator before removing it and replacing the brushes and regulator?
Please educate.

Lorenfb

"Would my alternator diode circuit not at least cause the dashboard warning light to come on if the regulator fails?"

Remember, one side of the alt. light is connected to the #15 (key on battery).
The other side is connected to the regulator and plus side of the field winding.
The regulator switches (on/off) the other side of the field to ground.

If the alternator fails "on", then the field is always switched "on". Thus both
sides of the alt. light basically "see" the same voltage and remains "off". The only
real way to have the alt. light indicate an overvoltage condition is to modify
the Porsche wiring and add additional circuitry beyond just a diode.

Bottom line: A reliable monitoring system ALWAYS requires an additional and
SEPARATE circuity, i.e. in addition to the regulator itself. You really can't reliably
have a device monitor itself.

"Can you tell me exactly what is the original 3.2 90 amp alternator, where it is available and how one can prevent cooking one's battery prematurely?"

The OEM alt. is a Paris-Rhone (Valero) and can be purchased via major parts suppliers,
e.g. SSF & Worldpac, & IMC.

There's really no way to prevent overcharging wihout adding additional
circuitry and wiring modifications.

theiceman

true but you can certainly monitor for it by wiring in a simple discreet voltmeter..

der Mond

Have you wired this separate circuitry into your 911 and could you explain how the rest of us could? Is it hard for a person with basic DIY skills and a multimeter and soldering gun?

Lorenfb

"Have you wired this separate circuitry into your 911 and could you explain how the rest of us could?"

No, it's not worth the effort as the later (>'00) Paris-Rhone regulators are reliable,
i.e. not like the orignial units ('84-'89).

der Mond

Loren, please be patient with me, I'm trying to understand just enough to hopefully not be dangerous...
If the newer units are reliable,
and does this include rebuilt Valeo units from, say, Vertex?
Then, since no alternator lasts forever, does not the issue still exist of knowing precisely when the unit is beginning to overcharge, prior to smelling it as a result of damage already being done?

der Mond

Iceman, have you wired in the simple discreet voltmeter? How and where is the guage visible?

theiceman

I mounted mine to a small piano hinge and mounted it to the underneath of the ashtray. I hooked it to a yellow I believe wire. This is just a switched 12v supply. I also hooked a wire to the headlight swtich so it is back lit at night. I was having some problems with my alternator so I did this. if I don't feel like looking at it or it gets in the way I just push it forward it it folds up out of the way .

ice PS it alwys reads about 13.5 volts with the engine running .

I can't remember exactly but I used a meter to find a wire that was hot with ignition on ( voltmeter ) ,one that was hot with the lights on and a ground..

der Mond

Cool - where did you connect the other wire?

Lorenfb

"If the newer units are reliable, and does this include rebuilt Valeo units"

I don't have any idea what rebuilders are using for regulators and even if
they replace them. It's only the new alts. that I'm sure about having the
updated regulator.