jheis

My '82 has only seen occasional use recently and has, pretty much been sitting outdoors for the past couple of years. This is northern California, however, so other than some dampness, it hasn't seen weather extremes.

When I put it back in service a couple of months ago, I had no gauges - nothing in the instrument panel worked. I thought maybe it was a sticking relay, but following someone's suggestion I cleaned the grounds up under the steering column and that brouht the instruments back to life - except for the voltage gauge - which has not worked for several years. The voltage gauge started as an intermittent problem, but eventually stopped working entirely.

Anyway, the instruments stopped working again after a coupe of months, so I pulled all the relays and fuses and cleaned the connectors with scotch bright and CRC electrical contact cleaner - no joy. Replacing the turn signal flasher brought the instruments back to life.

Most recently, I noticed that the light in the non-funtioning voltage gauge seemed to be glowing faintly. Adding a load made it glow brighter.

My alternater is a Bosch rebuilt Paris-Rhone (at least it came in a Bosch box and has a Bosch sticker on it). The rebuild is a few years old, but only has about 10k miles on it.

When the ignition is turned on, the lamp at the bottom of the voltage gauge glows brightly, so I assume the alternater was seeing exciter voltage. I thought that maybe the voltage regulater had gone bad, so I replaced the Valeo regulater with a new HÜCO unit.

After reinstalling the alternater with the new voltage regulater and reconnecting the battery, the exciter lamp was lit with the ignition OFF and went out when the ignition was turned on. The lamp came back ON when the ignition was switched off and stayed ON - even with the key removed from the ignition!

I had to run some errands, so around town, the battery was drained after about 5 or 6 (daytime) starts.

Since the voltage lamp was acting backwards (ON with the ignition OFF and OFF with the ignition ON) I thought that maybe I had reversed the polarity when I installed the new voltage regulater (altiough I had connected the blue and yellow leads in the same orientation as they had been before).

I figured I'd pull the alternater again today and see if I couldn't get it working, so I made sure the battery was fully charged and went out to tackle it again today. When I started the car up, however, the voltage lamp was acting normally, i.e., off with the ignition off and on with the ignition on and off with the engine running.

With the engine off, I'm reading a little over 13v at the jump post (fully charged battery). With the engine running I was seeing about 15v at idle with the engine cold, dropping to about 14.5 volts as the engine warmed up. Reving the engine increases the voltage reading to as much as 18v.

The lamp in the voltage gauge is, however, once again, glowing faintly at idle and brighter as revs increase. I also noticed that the seatbelt indicater lamp was also glowing brighter with revs. The ignition alarm "buzzer" is also staying on with the doors shut and the engine running.

I'm scratching my head, so any suggestions would be appreciated....

James

Mrmerlin

you need a PR regulator the huco will not work properly,
this happened to one of the cars I was working on.

NOTE over voltage can kill the engine computers dont keep testing this alternator like this

NOTE you can also swap out the PR alternator for a fresh rebuilt Bosch unit you will then need to buy a new airduct as the PR will not fit Bosch

jheis

Well, that was disappointing. Over 100 views and only one response....

According to Stan, the HÜCO regulator won't work with the Paris Rhone alternator - even though that's the regulator that everyone seems to list for the '82 - which has a Paris Rhone alternator. Physically, it has the same form factor as the Valeo regulator which came on the Bosch re-built Paris Rhone.

I reinstalled the Paris Rhone with the original (Valeo) regulator today and I'm seeing about 12.6 at the jump post with the ignition off which drops to about 12.4 with the engine running at idle - so it is discharging rather than charging.

Stan also suggested installing a Bosch alternator to replace the PR. I do have a Bosch alternator (928 603 011 01) which (IIRC) came with the '84 engine that I bought as a spare years ago . I thought I'd try installing the Bosch alternator today, but it has a 6 rib pulley rather than the 4 rib pulley on the Paris Rhone. I could swap out the pulleys, but it is also physically larger and mounts differently, so installing the Bosch was a no go.

Bosch on the left, Paris Rhone on the right.

The Forgotten On

That bosch is an al115x for a 32V car ( the 84 probably had its bracket changed to fit that).

The one you need is a al325x. It is still sold new for ~$350 and uses the stock alt shroud the PR unit uses.

jheis

I thought that the Bosch alternator pictured came on the '84, but it could have come from an 86.5 that I helped part out - I really don't remember where it came from...


The alternator that's in the car now is a "Bosch" rebuilt Al325x - which is a Paris Rhone alternator. It was rebuilt by Bosch, came in a Bosch box and has a Bosch AL325x sticker on it, but it's a Paris Rhone alternator.

Mikebte

As I am sure you have read, having good electrical connections can go a long way on the 928. Sounds like the car has some connection issues and your currently on the alternator. If you have not spent a weekend cleaning ground points and cleaning all the contacts you can find, you will most likely end up with more issues once you resolve this issue.
May be a long shot, but sure worth a try. I can tell you from experience, clean all the connections you can and the car will be nice to you.

If you have completed this already, have you removed the gauge cluster and inspected the plastic circuit board on the back?

Mrmerlin

James I dont know what else you could ask for.
The issue I had is exactly the same as what you have.

I found the same issue with overcharging and strange gauge and lamp indications,

How I fixed it was by replacing the Huco regulator with a Paris Rhone regulator.

NOTE the HUCO part is less expensive so thats a prime reason to use this part.
Turns out its not the right part for this alternator,
it causes it to operate at higher voltages this can kill the computers and fry the battery.

NOTE also inspect the 14 pin connector for shedding insulation or corroded pins

jheis

Sorry Stan, not doubting you, just trying to come up with the right regulator for my alternator. Do you have a part number? Nobody seems to list a "Paris Rhone" regulator.

My parts guy (who is also a 928 owner) got me the HÜCO regulator for my '82. PN 911 603 913 01.

This is the regulator his parts suppliers list for a '82 928. In trying to research this online, I see that "Landseer" had posted a reference to a "new voltage regulator" Tech Bulletin on Pelican which gives the new part number as 911 603 913 01 - which is the same part number as the HÜCO regulator which I have (and with which we both have experienced over voltage).

Pelican shows four different versions of the voltage regulator - all with the same 911 603 913 01 part number. Of course they also refer to all of them as "Marchal." So, I guess all frenchmen look alike....

The original regulator was a "Valeo" YV2700. So, where do I find a regulator to replace it - other than the HÜCO - which everyone seems to list as a direct replacement - but doesn't work?

What did you use? Thanks.
James

Mrmerlin

I bought a PR regulator off of Ebay it was 97.00, The Huco was 24.00 this was 7 years ago now.

I would suggest to look on google to see what they should look like and then call Roger he may have these in stock

dr bob

Check with our regular suppliers for a complete rebuilt unit and quit screwing around trying to patch the old one. The risk is great for damaging stuff with over-voltage in the system. Plus buying a Bosch-factory rebuilt unit, even if it was a PR or Marchal in a past life, is a lot cheaper than buying even the basic repair pieces.

If you want to play around with trying different regulators, do it on a "test bench" with a motor and a battery.

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Voltage regulators, at least modern ones, just don't fail unless they are subjected to some kind of abuse. Might be heat, likely from overloading trying to charge a failed battery. Brushes and slip rings seem like the major wear items in an alternator, along with bearings. If the rest of the electrical system is in good shape and maintained that way, the bearings should probably wear out before any electrical parts give up. Of course, worn bearings will lead to some mechanical then electrical failings in windings. So the best protocol is probably to replace wear parts at some predetermined interval, before the cascade failures start to happen.

Or just get another one when yours craps out.

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I bought a Bosch rebuilt unit for my S4, part of a shotgun approach to solving some battery and charging symptoms. It was statistically due at 100k, even though those were mostly low-RPM cruising miles. The original alternator still has plenty of brush left and the slip rings are fine. I put new bearings in it "just because" after a through cleaning, bagged it and put it in the "removed original parts" bin. The finish is the original smooth cast, vs the replacement that's not -exactly- the same. It did nothing for the battery and charging symptoms, by the way.

docmirror

An alternator with a wrong regulator can operate kind of like a motor, and draw a small amount of current from the system which is why your needle worked opposite normal. It's rare, and looks strange but it can happen.

Over-voltage - you've been warned. Charging over regulated 14.9 volts(depending on where measured) will eventually damage the battery, and more voltage will damage the circuitry.

Stan gave you the solution to the regulator issue. Get that taken care of first. After that, it sounds like you have some issues with the indicator wiring. The harness across the front of the engine to the 14 pin is notorious for causing indicator issues, so look at that.

as a general rule, clean all your grounds, and replace the big ground strap at the rear. Clean all your terminals around the + of battery, and only use your handheld voltmeter for taking measurements. Ignore what the dash voltmeter says until you get this stuff sorted out.