92 SL1 alternator out again

Maybe someone has some deep insight into this. I thought I knew all the answers, like "if your alternator goes bad then the alternator or battery light will come on on the dash", but that's never been the case. Our 16-year-old 92 SL1 had the alternator conk out last Friday, and the only light that came on on the dash was "Shift to D2". At the same time, funky noises were coming out of the radio and the engine was pretty obviously having a hard time. Exact same symptoms as previous alternator failure.

I know all those things are sensitive to voltage, and that "Shift to D2" came on because maybe the transmission is more sensitive than the others, but still: why doesn't the alternator or battery light come on?

I think I remember hollering at somebody in this newsgroup, probably

15 years ago, saying that if the alternator fails then the alternator light will come on. But in real life, it doesn't!

I spent Saturday morning taking the old alternator out and then, in about one fifth the time, put the new one in. Geeze, you'd think that after having done it before I'd remember how to orient the damn thing to get it out more easily... but it had been like 8 years now, so I struggled! The key is: take off the power steering pump. Loosen the PS hoses from the clip on the bottom. Then move the PS pump all the way to the firewall towards the center of the car. With it arranged like that, it's a breeze. Next time, I'll remember! At a new alternator every 8 years, that'll be 2016...

Tim.

Reply to
Tim Shoppa
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Sounds like it may have been a diode failure. When a diode shorts an ac voltage is added to the DC. Battery damps some of this but it is bad for both the battery and any electronics. Just out of curiosity, did you really wind out the engine before you found the alternator was bad? The only wear items on an alternator are the brushes for the field circuit and bearings. Sometimes the diodes go but when this happens, more often than not, they short in pairs which effectively shorts the output of the alternator. Belt starts screeching then.

Reply to
Oppie

I'm pretty sure all my alternator failures have been either single diode or regulator failures. The alternator just quits charging the battery. I hook up my meter, start the engine, and the voltage never goes up like it should when being charged - just down. I can't tell you that the alternator is really putting out zero current, just not enough to charge the battery with all the accessories off and the engine running.

My mother-in-law's early-90's Oldsmobile used a Delco alternator that seemed nearly identical to the Saturn's, except that the mounting brackets were at a different angle. When it failed, the alternator light actually came on. Not sure if it was electrically different or identical, but the connectors were identical to the Saturn's.

In my experience, the best quality rebuilt alternators seem to outlast the original Delcos. The originals seem to last 4 or 5 years, and the rebuilds maybe 10 years. (Actually we're driving the Saturn more than in the past, so if you measure it mile-wise the rebuilt lasted 3 or 4 times as long as the original.) Maybe the best quality rebuilds have better, more durable diodes/regulators/???

Tim.

Reply to
Tim Shoppa

I'm pretty sure all my alternator failures have been either single diode or regulator failures. The alternator just quits charging the battery. I hook up my meter, start the engine, and the voltage never goes up like it should when being charged - just down. I can't tell you that the alternator is really putting out zero current, just not enough to charge the battery with all the accessories off and the engine running.

My mother-in-law's early-90's Oldsmobile used a Delco alternator that seemed nearly identical to the Saturn's, except that the mounting brackets were at a different angle. When it failed, the alternator light actually came on. Not sure if it was electrically different or identical, but the connectors were identical to the Saturn's.

In my experience, the best quality rebuilt alternators seem to outlast the original Delcos. The originals seem to last 4 or 5 years, and the rebuilds maybe 10 years. (Actually we're driving the Saturn more than in the past, so if you measure it mile-wise the rebuilt lasted 3 or 4 times as long as the original.) Maybe the best quality rebuilds have better, more durable diodes/regulators/???

Tim.

I had a nippondenso alternator on a Chrysler minivan I used to own. Original failed and I replaced it with same type. It failed within a year. Diodes shorted to the point that I had to cut the drive belt to drive the car. Was hard-wired so unplugging was not an option. Luckily this was not a serpentine belt. Later found out that the 'denso alternators had a bad reputation. I replace it with a Bosch that worked well till we junked the car. The only problem with the Bosch was noise on the radio. Was going to put in a suppressor but never got arround to it. I would guess that the Bosch had different diodes that gave more noise. (High speed diodes have a current spike when they switch from conducting to blocking)

Reply to
Oppie

You don't always get the idiot light when an alternator goes. That's why I have a voltmeter gauge in my car.

Reply to
zzyzzx

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