924Board.org

tuf-924 · Joined: 05 Nov 2009 Posts: 119 Location: wollongong

Hey guys tried to start my car today the battery was completely dead, roll started the car this morning, the car ran well but the valtage did not exceed 10 volts and kept dropping to 8 then back to 10 got to work now battery Is flat again, any one else thing alternator is stuffed? Or could it be the battery not holding charge? Or another problem?
_________________
Vass...

emoore924 · Joined: 13 Apr 2004 Posts: 2822

Sounds like the altie isn't working. Should be 14-ish volts when running/charging. Do the obvious stuff like check the belt, make sure you read up on the bulb, the wiring, the mounts and all that, then remove and test it, replace as necessary...

Ozzie · Posted: Thu Oct 27, 2011 11:25 am Post subject:

Does the charging bulb work? It must work before starting.

Wiring loom could be fried.- known fault.

Alternator regulator and brush unit failed?

Alternator belt loose?

Alternator failed.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

stevekat · Joined: 19 Jan 2008 Posts: 719 Location: Los Angeles, CA

The alternator warning light is a key component of the charging circuit. If the warning light is burnt out, the alternator shall not charge. Crazy but true. So make sure it lights when the key is in the 'on' position, (the position just prior to the 'start - crank starter position on the ignition switch.)
_________________
"Never get out of the boat. Absolutely goddamn right. Unless you are goin' all the way."

Gone to new home: '81 924T, US version, CGT Intercooler, UTCIS-PT, Euro DITC, Greddy Trust MBC, Forged Fuchs Flat Dish 6's, Factory Recaro's.

tuf-924 · Joined: 05 Nov 2009 Posts: 119 Location: wollongong

The battery light is on before cranking, and while running it is turned off, I charge the battery yesterday tested the charge circuit while car was running and alternator seemed to be charging it, it was running at 14.5 volts, but the car volt tacho was reading 10 volts and less. This morning before work it started fine, but as soon as I got to work tried to start it again just incase nothing worked again.
_________________
Vass...

Ozzie · Posted: Fri Oct 28, 2011 7:38 am Post subject:

Go through the list.
the wiring is always suspect.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

stevekat · Joined: 19 Jan 2008 Posts: 719 Location: Los Angeles, CA

Careful driving. The battery goes too low the fuel pump may not run, if the alternator is not producing adequate output. Then you are stuck.
_________________
"Never get out of the boat. Absolutely goddamn right. Unless you are goin' all the way."

Gone to new home: '81 924T, US version, CGT Intercooler, UTCIS-PT, Euro DITC, Greddy Trust MBC, Forged Fuchs Flat Dish 6's, Factory Recaro's.

porscheboy79 · Joined: 25 Oct 2010 Posts: 65 Location: Sydney , Australia

Check the fat wire first from the back of the ALT.

I have seen a few now and they are always brittle and suffering corosion on the inside. The high heat from the exhuast kills them!
The heat bakes the insulation and the heat helps moisture get carried down the inside of the wire.

Hope you get it..

Shane
_________________
79 924. 100kph + wall at Mt Panorama = Gone.

77 924 SPIRIT project for racing.

tuf-924 · Joined: 05 Nov 2009 Posts: 119 Location: wollongong

Cheers for the advice and the support guys, Actually steve now that you mentioned that the car might stop reminds me it did stop about 8 months ago i thought it was an ignition problem and lack of fuel pressure, but it makes sence this whole time it's been low voltage, I'm going to check out the wires tomorrow and if they are good I'll send the alternator to be checked by my auto electriction I'll see how i go, also seems that something is draining the battery power it doesn't want to keep charge but at the same time does not go completely flat. Like today i left the car for about 5 hours after incouldnt start it and it actually started the battery got enough voltage to kick the car over after leaving it for 5 hours. I'm so confused
_________________
Vass...

emoore924 · Joined: 13 Apr 2004 Posts: 2822

Sometimes you can have a bad diode in the alternator that will make it into essentially a big electromagnet when the car is stopped. Of course, that'll kill your battery after a bit, but it would usually be accompanied by a very dimly-lit alt light when you're running.

I'm also a bit suspicious of your in-car volt gauge. Can you run the car around for a while with a handheld voltmeter or something to see what voltage you're really getting at the battery from the alternator...?? Bad grounds can make the gauge wonky.

If the charge voltage is good, and the alt tests good, you probably have a bad battery... When was it last replaced?

stevekat · Joined: 19 Jan 2008 Posts: 719 Location: Los Angeles, CA

In any case when the fuel pump wouldn't run due to a charging problem, you would probably know you had no power or almost no power. The car wouldn't not crank, probably no accessories would work, lights would be dim or not illuminating at all. Even if the alt. was not charing at all, the battery would also need to be nearly fully discharged to prevent the pump from running. .
_________________
"Never get out of the boat. Absolutely goddamn right. Unless you are goin' all the way."

Gone to new home: '81 924T, US version, CGT Intercooler, UTCIS-PT, Euro DITC, Greddy Trust MBC, Forged Fuchs Flat Dish 6's, Factory Recaro's.

!tom · Posted: Sat Oct 29, 2011 6:11 am Post subject:

tuf-924 · Joined: 05 Nov 2009 Posts: 119 Location: wollongong

The battery was replaced 8 months ago the new And old battery do the same thing it didnt help at all.

Well the car struggled to crank the other day that's when I roll started it then charged it at work it was good for a dAy then died again. And ye when I turn the lights on they dim and if I put the fan on they dim even more and then the radio if I put that on it cuts out the turns on and cuts out and this happens every time constantly
_________________
Vass...

!tom · Posted: Sat Oct 29, 2011 2:42 pm Post subject:

Bad grounds?

Check the engine ground, and the battery ground. When I say check, that means disassemble, clean, and reassemble, hopefully protecting the connection with electrically conductive grease.
_________________
78 924 NA
5-lug

tuf-924 · Joined: 05 Nov 2009 Posts: 119 Location: wollongong

New theary to problem, starter motor don't like to start while hot, no power get to starter at all once turned off after a good drive, after 30 mins car starts but fairly weak power but still kicks over, I have a feeling the starter is draining all the power some how. Or it cuts off the power at a curtain temp.
Does anyone have anything to say about that
_________________
Vass...