alternator/underdrive pulley problem?
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From: Daytona Beach
alternator/underdrive pulley problem? My gauge has been showing very low voltage...like in the red. I put i meter on the battery and it said 12.2ish and the alt said 12.4ish...which is low. Went and got another new alt and out it on. Right out of the box the guage is perfect, 14.5 off the alt and 14.1 at the battery. Let it idle and it dropped down to 12.4 at the alt and 12.2 at the battery with a low gauge reading again.
So..i put the old one back on. And it did the same thing. for the first 5 min it read perfectly at 14.5 at the alt and 14.3 at the battery. Let it run for 10 min and checked it again. Now is back into the twelves again and back in the red on the gauge. The wiring is fine, there is only a small drop from the alt to the battery. IM LOST
Some friends are thinking its the underdrive crank pulley..any thoughts?
So..i put the old one back on. And it did the same thing. for the first 5 min it read perfectly at 14.5 at the alt and 14.3 at the battery. Let it run for 10 min and checked it again. Now is back into the twelves again and back in the red on the gauge. The wiring is fine, there is only a small drop from the alt to the battery. IM LOST
Some friends are thinking its the underdrive crank pulley..any thoughts?
Launching!
Joined: Dec 2004
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From: Hebron, Oh
That could be your problem. The smaller crank pulley will slow all your accessories down. I put the overdrive alt. pulley along with the crank pulley to speed the alternator back up. I have never had your problem. Did the problem start after you put the crank pulley on?
I agree, when you have an underdrive pulley on the crank, you need the overdrive pulley on the alternator. I ran mine without the overdrive pulley for about a year, then the battery died while I was idling in line at the track. Some bozo had dropped his tranny on the track so we had to wait a long time. I installed the overdrive pulley, and no issues whatsoever since then (5+ years).
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From: Daytona Beach
where can i get just the alt pulley? any thoughts?
is it odd though that the car ran for 10 odd minutes at over 14 volts and gradually worked its way down..you would think if it was not charging enough it would do it all the time.
is it odd though that the car ran for 10 odd minutes at over 14 volts and gradually worked its way down..you would think if it was not charging enough it would do it all the time.
Maybe check grounds and then call it a day, if it hasnt died on you, i wouldnt worry about it too much. You could always go back to the stock pulley. You think youll miss the added HP over the drivability? I doubt it....
-justin
-justin
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From: Daytona Beach
yes it does...but only to around 12.8-13.1 at the alternator..thats just enough to keep the battery charging..it still doesnt even make it to the halfway mark on the dash gauge (but im not using that has a end all be all)
When you are at a light at night. The lights can get so dim it can be hard to tell the are on.
When you are at a light at night. The lights can get so dim it can be hard to tell the are on.
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Verdad Gallardo It should climb up to around 13.5 tops. You may have a general charging problem instead. The best way to troubleshoot would be to put the stock pulley back on (along with a longer belt) but you probably don't have the stock pulley, since it came with the underdrive pulley on it.
I would start by pulling the alternator and taking it to an autoparts that will check it for you. Almost sounds like a part is overheating after it warms up.
I would start by pulling the alternator and taking it to an autoparts that will check it for you. Almost sounds like a part is overheating after it warms up.
I had the same problem, I bought the car with an underdrive setup on it, I went to a local business rebuilds starters and alt. I asked them for the smallest pully they could get on my alt., they hooked me up with a free pulley. I put a 1" shorter belt on, problem solved.
Thread Starter
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From: Daytona Beach
It should climb up to around 13.5 tops. You may have a general charging problem instead. The best way to troubleshoot would be to put the stock pulley back on (along with a longer belt) but you probably don't have the stock pulley, since it came with the underdrive pulley on it.
I would start by pulling the alternator and taking it to an autoparts that will check it for you. Almost sounds like a part is overheating after it warms up.
I would start by pulling the alternator and taking it to an autoparts that will check it for you. Almost sounds like a part is overheating after it warms up.
and i do have the stock pulley, just need new bolts. An underdrive on these cars bolts to the stock harmonic balancer so i still have the OEM one.
well its now done the same exact thing on three diff alternators. The alternator that was checked is this one and it checked out perfect (amps and volts).
and i do have the stock pulley, just need new bolts. An underdrive on these cars bolts to the stock harmonic balancer so i still have the OEM one.
and i do have the stock pulley, just need new bolts. An underdrive on these cars bolts to the stock harmonic balancer so i still have the OEM one.
well its now done the same exact thing on three diff alternators. The alternator that was checked is this one and it checked out perfect (amps and volts).
and i do have the stock pulley, just need new bolts. An underdrive on these cars bolts to the stock harmonic balancer so i still have the OEM one.
and i do have the stock pulley, just need new bolts. An underdrive on these cars bolts to the stock harmonic balancer so i still have the OEM one.
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