ben951

i have an 86 951

i replaced the starter and the battery, and withn about a week the battery was dead, and would not even make the starter click, although the electric windows and smaller things like that work.

the meter on my dash usually shows about 12 before the engine has started, and then while the engine is running is usually between the halfway point or lower, although it jumps up and down if i use any electrical items in the car, if i roll down the windows, the meter shows 12 while my finger is on the switch, and goes back up again as soon as i remove my finger, the same happens when i use the heater, but not the radio.

I have taken a look at the alternator and it looks in pretty good shape, looks clean and new, although i couldnt say for sure that it was.

My question is, could it be the voltage regulator that is responsible for all of this?

sillbeer

I'm curious about this as well. Something is draining my battery and I can't figure out what it is. It only drains it sometimes. Usually when I go somewhere to get gas I need a jump to get it started again but when I get home it'll start right up. I have put a volt meter on the batter while it is just sitting and I can watch it go from 12.8 down to 12.4 in about a 15 minute time frame. I just put a new Optima red top in it along with a new batter ground and engine ground. I can't figure out what it is.

-destin

951Porschiste

You said you "looked" at the alternator as in just inspecting it visually or actually having it check out at your local auto parts store?

Sounds like the alternator might be the problem or you have a bad ground somewhere. Now, if you decide on having the alternator checked, you will have to remove it from the car. That in itself is not a difficult job per se but it is long and tedious in a 951. You have to drain the coolant, remove the airbox, the AFM, the IC pipes, the "J" boot, some vac lines, some coolant hoses, etc. etc.

Good luck!

ben951

it was just a visual inspection on the alternator, i didnt want to take it out unless i had to. If the battery is so flat that it wont even make the starter click, would it have enough power to operate the windows up/down at normal speeds like it is able to? i am just wondering if i should be looking at whether its the battery not being charged, or some sort of faulty starter switch, does this sound poosible given the symptoms?

sillbeer

I took my car to Autozone and Checker to have the alternator checked and it checked out good both times. They have a tester to hook up to your battery to tell if the alternator is working or not.

-Destin

951Porschiste

New battery that turns dead within a week, it's either:
1. Bad battery (it's been known to happen)
OR
2. There's something draining the battery (check your grounds!)
OR
3. The alternator is not charging the battery while you're running the car (meaning something might be wrong with the alt)

Edit: A low voltage battery can still operate certain electrical items on the car but not have enough juice to turn pver the starter.

jacklet

prolly a parasitic draw-meaning somethings drawing power when the car is off. Check the battery for a dead cell and check for proper charging function-a draw could be any number of things

951Porschiste

That's great. Makes diagnosing the problem much easier. If your battery is still draining then you have to look for other electrical gremlins. Happy hunting!

kwdrus

There is no need to drain the coolant.

bearone

check to see that the alternator light comes on when the key is on, it's part of the charging circuit.

87951

ben951

is the alternator light the red one under the voltmeter in the dash? if so, yes it comes on right before you turn the key to start the engine, as far as i can remember, it goes out right after the engine starts. if the alternator light is the one with the pic of the battery, no it doesnt come on, not even now the battery is dead, or i think its dead, im gonna buy a multimeter tomorrow and test the battery, if i put the meter across the terminals of the battery, what should it read in order to be able to start the engine?

95Juan

it should read around 12 or 11. probably 11 (IIRC).


note- you dont have to drain the coolant to get the alternator out. save yourself some time and just yank it out Incredible-Hulk-Style.


if i can do it with my banana hands, you can do it with hands that i'm sure are smaller.

bearone

if the bulb is bad and doesn't come on the batt won't charge.

the light is part of the electrical circuit, in series, like xmas lites.
if one's out, they're all out.

87951

ehall

Pull the battery and have it tested.
If good, run your grounds everywhere. Look for burned insulation on the ground wires.
If that's good, check the connection to both the starter and the alternator.
If good, pull the alt. and have it tested. A visual won't tell you a thing. Once it is out, there is no reason not to change the voltage regulator, considering you have to remove the alt. to get to it anyway.
BTW, have you checked the tension on the A/C -Alt belt?
Does the voltage guage move when the car is revved?

There is a start. Let us know what's up and we'll all help.
E

951Porschiste

... but removing some coolant hoses gives you more access!