Alternator woes.

Kinja'd!!! "The Snowman" (the-snowman)
07/24/2018 at 23:31 • Filed to: None

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Took my 41 to our local car show today, first show after 15 years of storage.

Anyway, the alternator problem is on my 85 c10. Voltage was reading low on the gauge so I went crazy with the multi meter and could never get over 12.5 volts even testing the output from the alternator and chassis ground.

So I replaced the alternator with a rebuilt one from O’Reilly’s it had the same problem for the first five minutes then magically started outputting 14 volts and I figured whatever it’s good now. Drove to work good voltage, time to come home gauge is re d multimeter is at 12.4.

I have even pulled the brand-new optima out of my other car to rule out the battery. And the regulator is built in on these alternators.

Any advice on what to try next? If I can’t come up with anything else I’ll go get a new rebuilt alternator and swap it in the parking lot since I’m under five minutes wrenching time now for the job.


DISCUSSION (10)


Kinja'd!!! If only EssExTee could be so grossly incandescent > The Snowman
07/24/2018 at 23:48

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Have you tried burning it down and buying a new car? That’s what I do when I encounter electrical gremlins and it seems to work pretty well.


Kinja'd!!! The Snowman > If only EssExTee could be so grossly incandescent
07/25/2018 at 00:04

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This is a nice enough c10 that I carry full coverage on it. Also say no to insurance fraud.


Kinja'd!!! 415s30 W123TSXWaggoIIIIIIo ( •_•))°) > If only EssExTee could be so grossly incandescent
07/25/2018 at 00:42

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Fortunately I bought my M37 after they installed a whole new GM wiring harness! Yay! My old Mercedes has a couple weird things going on though , I may bring it to the Swiss Garage near me to see if they can figure it out, one is a power drain on fuse #2, I can’t figure out what the hell it is.

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Kinja'd!!! If only EssExTee could be so grossly incandescent > 415s30 W123TSXWaggoIIIIIIo ( •_•))°)
07/25/2018 at 00:48

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What vintage of M er cedes is it? If it’s an e arly 90's car you might be fucked.


Kinja'd!!! 415s30 W123TSXWaggoIIIIIIo ( •_•))°) > If only EssExTee could be so grossly incandescent
07/25/2018 at 00:57

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On no it’s a w123, 300D turbo . It is probably not a big deal for a professional. I myself believe electricity is witchcraft and juju.


Kinja'd!!! If only EssExTee could be so grossly incandescent > 415s30 W123TSXWaggoIIIIIIo ( •_•))°)
07/25/2018 at 01:04

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For a bit in the 90's Mercedes decided to “go green” and install biodegradable wiring harnesses in their cars. Problem is, the wiring started to biodegrade a few decades too early and you ended up with a harness that looks like this:

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Kinja'd!!! DC3 LS, Fuck Hyundai, now and forever > The Snowman
07/25/2018 at 01:09

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If it’s a denso alternator, I’d see if you can by the regulator on it’s own (assuming that’s the problem). I did that on the Integra and I think the regulator was half the price of a parts store alternator. And on the Denso units it’s easy to replace. You could probably do the brushes too while your at it, if you think they might be an issue. 


Kinja'd!!! 415s30 W123TSXWaggoIIIIIIo ( •_•))°) > If only EssExTee could be so grossly incandescent
07/25/2018 at 01:17

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I have heard of that, it’s returning to the earth!


Kinja'd!!! Zaxbys > The Snowman
07/25/2018 at 12:48

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I’d take a multimeter and start che ck ing voltage drops between the alternator, battery, and chassis. With any luck, you’ll find your dropping voltage between  two  of those, and you can look into replacing/fixing the connection wire. My guess (which is just that - a guess) would be the grounding of the alternator which probably uses the engine grounds.


Kinja'd!!! Jayvincent > The Snowman
07/25/2018 at 18:58

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I agree with Zaxbys below, it’s probably a bad ground wire or connection... but if it’s not, Ive been burned before with re manufactured alternators. After the third one in less than two years , I bought a new one for 2x the reman price and never had another problem.