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Guest Message by DevFuse

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Alternator bad?? I'm an idiot...

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9 replies to this topic

#1 lastchance


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Posted 14 January 2004 - 09:19 PM

1984 turbo wagon....

At normal driving everything is great...Lights work good, stereo, volts are pegged where they should be....But, when I come to a stop in my headlights get dim and my volts drop quite a bit, not into the red but, it's noticeably lower...It also is worse when my blinker and brakes are on (the volt needle jumps up/down/up/down at a low rate of voltage). So when I hit the gas to get going, the volts go back up and lights brighten up.

Here's what I've troubleshot so far...

Just replaced the the alt. belt, checked tension, everything is all good...Didn't cure the problem.

Turned up the idle from about 450-500 rpm in drive at a stop up to about 600 rpm (750-800 at idle, which is what Subaru recommends)

Well....My next troubleshooting step is you guys...Hopefully you can help


#2 Turbone


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Posted 14 January 2004 - 10:03 PM

Take your battery in and have it checked. It may have a bad cell, or could just be getting old.

#3 torxxx


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Posted 14 January 2004 - 10:49 PM

check the water level in it if its a maintenece free battery
if its low, you gotta use rain water (water without minerals)

if the waters low in the batt. if wont hold a charge

#4 Danbob99


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Posted 14 January 2004 - 11:13 PM

well, my soob does the same deal, i think, but it just means that your alternator isn't putting out as much when it's not at rpm. It's nothing out of the ordinairy, unless its endangering the running of your car. if your volts shoot throught the rough, your "brake lamp", "check engine" :charge battery: lights all come on at once, your alternator is not putting out (they will come on on start up regardless) but if your car idels, starts, and runs fine. it's perfectly normal.

#5 Turbone


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Posted 14 January 2004 - 11:34 PM

Did you replace the Alt with a new one?

#6 Flowmastered87GL


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Posted 15 January 2004 - 01:30 AM

My volts go down a bit when I get down in the 700 RPM range (the red lights DONT come on though) The voltmeter moves a bit with the turn signal flashing too. Its always done it, even when my 5 year old battery was new and with my hitachi alt, and my 3 autozone ones since that one blew.

If its SUPPOSED to do that I am unsure. But I dont worry about it. I just made my idle 1200 or so :D

#7 richierich



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Posted 15 January 2004 - 02:03 AM

Have you had the voltage system checked under load (ie with the lite, etc) with a independent voltage tester? No just the lite on the dash? The dash system is not always know to be accurate. There also could be a loose connection somewhere.

Like everyone else, check the battery.

#8 Skip


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Posted 15 January 2004 - 06:37 AM

Dan, I agree with Rich, have the no load voltage checked. Should be in the range 13.8 to 14.2 Vdc.
This could be normal operation but...
You say
"volts are pegged where they should be...."
The voltmeter should not be "pegged", maybe you just used that to indicate where the needle is ?? but...
This is a sign of over voltage, these alt.s are famous for this.
Sounds like the internal voltage regulator is knackered.
I read you have a new alt "belt" not a new alt. is that correct?

#9 riverrat


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Posted 15 January 2004 - 09:17 AM

I would have to agree with the advice of having the charging system tested.A couple of bucks if not free that will save a lot of guessing.Once one piece of a charging system starts to fail the next piece in line takes the abuse and wears out to doubling the cost.

I also know from experiance that a new aftermarket alternator does not mean it is good.The only one I have ever had to replace on a suby came out of the gate charging anywhere frome 19v to 9v.did not need a volt meter to tell just turn on the lights.Napa tested it and told me it was fine.had to take it out of town to a differant napa{differant management] to get the truth.I got the idiot at the local store fired over that one.

#10 Meeky Moose

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Posted 15 January 2004 - 10:05 AM

this little hatch does the same thing, but only when i turn everything on..

have to have the high beams, heater on high, stereo on, front and rear wipers on high, step on the brake.. then turn the blinker on and the volt gauge bobs up and down but right at 12v when it does.. never lower than 11v..

but with everything off like normal day driving, it stays around the 13-14v area..

my idle is about 850-900.. gotta tune the hitachi some and clean it, its startin to stick at 13-1500 now :(

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