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[TOM087]

the battery in my 77na hasn't been charging, and will completely discharge in a matter of hours (5hrs is its PB!).

The alternator seems like a likely source of the problem (the battery itself is less than 2yrs old).

Belt tension seems fine, although the cooling hose has disappeared. I'm wondering if the absence of the cooling hose has cause diodes to fail?

I bought a digital multimeter the other day to try and isolate the problem, but i'm not sure how to test the alternator when the car won't turn over (last time i jump started the car it died as soon as i took my foot off the accelerator). Is there such a way?

I also suspect some fuses might need replacing, but again i'm not sure how to test this without the car running (i've checked them for resistance but i'm not sure how to interpret the findings)

Cheers in advance for any and all help!

Tom
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1977 Martini Rossi

[Harm]

My experience:
Failing (corroded) main power line between the battery and starter: Replace that cable.

Also helpfull was the ‘How-To: diagnose electrical problems part one’
http://924board.org/viewtopic.php?t=19320&start=0&postdays=0&postorder=asc&highlight=&sid=a067333bc8a0e7c835c3db43a5e3419c

Wire looked good on the outside…



Regards, Harm.
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Porsche 924 NA 1982 LY7A/A3A3 _ Greater driving pleasure never harmed anyone.

[Rich H]

The easiest way to check fuses is to look at them, rotate them until the metal strip is facing you, if it's got a gap in it's blown.

Otherwise pull them out one at a time, if the metal filament is broken then you will see it. Normally the metal bits fall off the fuse case if they haev popped.

If they are corroded they might not work so well but rotating them around a couple of times will normally fix them for a bit.

To check the alternator charge the battery with a charger then start the car normally. Once the car is running put your meter (set on Volts) across the battery, if you charging system is working it will read 13.8v if not it'll read 12v. The cooling hose isn't much of a problem as long as the heat shield is there on the back of th alt still.

As above it is also worth looking at the cables.
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

[TOM087]

GREAT! thanks guys, i'll have a go at those over the next few days.

A typo in the heading though, i meant to type "relay" instead of "fuse"
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1977 Martini Rossi

[ideola]

A stuck relay can cause battery drain. An effective way to test them overnight is to remove half of the relays. If the problem goes away, then one of the relays you removed is stuck. If the problem persists, then the one of the relays still in could be the problem. Continue "halving" the number of relays in the panel until you isolate the problem. Just be aware that you could have more than one relay acting up. If you see any relays with evidence of corrosion or water damage, it is highly suspect.

Also, check to make sure the alt light on the dash is illuminating with the key in the on position but before you start the car. If that light is burned out, the alternator will not charge.
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erstwhile owner of just about every 924 variant ever made

[Joes924Racer]

* Nice Harm thats nasty been there donr that (though i built my own)
at the time.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.