kcfong2

1981 5-spd California 928, stock, L-Jet.

Hi all, for those who helped me find/locate a gas tank, I finally got the gas tank replaced (thanks Greg for providing it)... Now, the never-ending "something else just broke" just happened.

Was driving the car all day no problems, hit the freeway, and then noticed that my voltmeter (I have two... one on the dash that never reads right, and an aftermarket) was reading 12.1 volts, 11.8, and ultimately 10.8. I was able to limp to a friend on the way, and put a 15amp charge on the battery, then drove it home.

At home, I measure 12.5VDC at the battery terminals. When I start the car, it goes no where... maybe +/- 0.2VDC. I used to get 13.5 to 14.1VDC.

I would suspect the alternator, although I just installed a rebuilt last year. I haven't been having much luck with rebuilds however, (2 starters in 2 years with my MBZ), so I wouldn't be surprised if my rebuilt alternator went bad.

Before I put money and effort into R+R the alternator, are there any other points of interest on the 1981 US 928 that could affect charging? The voltage regulator came as part of the alternator rebuild. V-belt is fine, with good tension.

Just bad luck with a rebuilt alternator, or somewhere else I need to check? I should mention, it's got a new wiring harness (from Roger), so I doubt that's the cause.

One thing I noted however is that before this problem, turning on lights, A/C and the aux engine fan on would always drop the voltage down to 12.x. I would have to rev it up to get the voltage back to 13+ volts. Seems like the stock alternator can't keep up. I assumed this was normal.

Thanks in advance!

SeanR

Simon928

Is your alternator cooling hose/shroud intact? If not then that can significantly shorten the life of your alternator and could be a reason for it failing so quickly.

kcfong2

I will probably be reaching out to Roger shortly. I purchased a new harness from Rog a couple of years ago when I was "rebuilding" this... in fact, that's when I replaced the alternator...

That's why I want to confirm that there are no other unknowns when it comes to the 928 and charging... I don't know this car that well... I"m learning as I fix thing after thing <grin>. I am pretty certain it's the alternator, but if there's anything else, like some "module" that regulates charging... I want to know before I purchase and R+R the alternator again.

kcfong2

Yup, or should be. I replaced the shroud and hose a couple of years ago with parts from Roger. I'll crawl under tonight to have a look-see, but looking at it from the top, it appears all okay.