Got a problem and have no idea where to begin...

[ruechaos]

Ever since I bought my 84' n/a last month, it seems that the car is always draining my battery. Just the other day I bought a new battery (old one was too big) and the car drained the thing over night.

Now after replacing my rear bearings I took the car out for a spin on the highway at night. I had my headlights and my fog lights on, and my power windows down. On my return home I noticed that the lights were a little more dim than when I first turned them on, and then when I went to power the windows up it took forever for them to go up. The instrument panel lights also getting really dim.

My guess was the the altenator is not doing it's job and that all the lights were drawing on the battery, thus killing it by the end of the night.

But I want to hear your guys' opinions before making any assumptions.

Thanks!

-Tony

[Craig944]

Bad altenator?

[ruechaos]

How can I check the altenator and where it it located at?

Thanks!

-Tony

[p0r2chby]

Voltage regulator... do a search on the topic

[AFJuvat]

Sounds like a bad alternator or voltage regulator. - you didn't mention what your voltage meter was registering.

You may however luck out and just have a slipping belt - there should be little to no slack in the belt.

They are located under the airbox on the right hand side of the motor.

You can get an aftermarket alternator from discount auto parts for about %150 - which is much better than the $450 - 500 the dealer and most catalogs want

AFJuvat

[ruechaos]

I don't think that my 84' n/a has a voltage meter, unless it's hidden somewhere...

Thanks guys!

-Tony

[Ehab]

You can get a rebuilt alternator for about $100 from ebay ...

measure the voltage at the battery, it should be around 12.5 when off, and 14.0 when on. If the voltage varies with rpm, it is the regulator (part of the alternator, but removable) ... if not, then your VR is good, but you need to get the alternator professionally tested ... and since you're taking it out anyway, might as well put a rebuilt unit in ...

E

[88_944]

Yes, its a bad altenator.

------------------
PORSCHE There is no Substitute!
My 944 Site! http://www.skybusiness.com/dean/

[JonA]

Check the belt tension, do the easy stuff first!!!
If you have a multimeter, check the voltage at the battery with the car off and with it running and with it running under max elec. load (lights,fan,whatever). Engine off you should read battery voltage of 12v, running you should read aabout 13-14v, running under load you might read slightly less but certainly no lower than 12v.
Good luck.

[Andre]

easy way to check alternator. Start the car if it still starts(if not just jump it). Then unscrew the negative clamp off the battery and take it off the rod. If your car is still running your alternator is good, if it dies your alternator is bad.

[Britwrench]

Andre

If you disconnect the battery with the engine running, the alternator will be no good...!!!!!!!!!!!!!!!!!!

Not a good idea.

[88_944]

Originally posted by Britwrench:
Andre

If you disconnect the battery with the engine running, the alternator will be no good...!!!!!!!!!!!!!!!!!!

Not a good idea.

No, Andere is right. You can test the alternator this way. When the car is runing the car depends on the alternator for power but if the alternator fails, then the car has to depend on the battery for power and when the battery runs out, the car will die without 12V.



------------------
PORSCHE There is no Substitute!
My 944 Site! http://www.skybusiness.com/dean/

[mlue]

Donn't disconnect the battery while the engine is running you'll do more harm than good.

I suggest you buy your self a Haynes manual before messing with anything, they're available at most parts stores. The Haynes manual outlines a test that you can do to test the alternator. The Voltage Regulator/Brush Holder replacement is also outlined in the manual. Electrical schematics for your car are included and would be a valuable resource if the problem turns out to be more than what has been or will be suggested.

Mark
'86 944NA

[drew1]

I'm going to go along with everybody else.

1. Check voltage with motor running about 2500rpm. should be 13.5 - 14.

2. Ohm out the indicator bulb in the dash, this circuit sends volts to alternator field in some Porsche. (your model's wiring diagram will let you know)

3. Voltage regulator is on back of alternator & has a couple of brushes that go bad.


drew1

[Dave951M]

If you do take out the alternator, be sure to retorque the mounting bolts a day or two later, even if you torqued them when you reinstalled the alternator. They will loosen up because the brackets are aluminum and the bolts are steel and have dissimilar expansion rates. If you remove the bolts, they will "untorque" themselves. If the bolts loosen, the bracket can break, major pita time.

Dave951M

[DennisR_944]

When you disconnect the battery cable with the car running, you take a huge gamble. It can burn out your computer. Major $$$$$. Well...do you feel lucky. Do ya...

Dennis Russell

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Dennis Russell
Indianapolis, IN USA
1987 944 n/a

[Britwrench]

You know, I am having a hard time with this,
for all the time you've been discussing this problem you could have driven to a shop and they would have checked the alternator output, current draw and battery condition and explained what is wrong and what it needs to fix it...so far you still don't know exactly what the fault is...

[AFJuvat]

Good point... most places now can hook up a computer to the battery and test it all for you...

well, I guess sometimes, you can't see the forest for the trees....

still would not recommend disconnecting the negative wire from the battery while the car is running...

and definately, if you can help it, do not get an alternator from a catalog or a dealer... you can do MUCH better at parts stores..

AFJuvat