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Old 08-08-2010, 03:18 PM   #1
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Alternator

I realize this is not Subaru forum, but having just spent over an hour at the Subi site with nothing to show for, I come here for help.

My 2001 Outback is at it again. It needs a new alternator. (I have a gadget that tells me if the alternator is producing enough juice and it does not at idle.) This will be the FOURTH alternator for the car, counting the original, with less than 56k in over nine years.

Question:
1. What can I do to NOT kill my alternator so often?


Thanks in advance.

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Old 08-08-2010, 06:23 PM   #2
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But doesn't

an alternator not produce its top "juice" till 2-3k RPM? I recall the testing is not done at idle. And I recall jump starting others cars, the best results were after reving the donor car's alternator to 3k for a bit.

Is the Subi's voltage regulator part of the alternator or separate?

Connections clean and secure?
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Old 08-08-2010, 09:21 PM   #3
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Smell

Quote:
Originally Posted by mikefocke
an alternator not produce its top "juice" till 2-3k RPM? I recall the testing is not done at idle. And I recall jump starting others cars, the best results were after reving the donor car's alternator to 3k for a bit.

Is the Subi's voltage regulator part of the alternator or separate?

Connections clean and secure?
Thanks for your interest Mike.

Well, I am thinking my alternator is bad because,
1. There is this burning smell when I open the hood.
2. According to my gadget, the alternator is producing a little bit more than 12v at idle. And the gadget says this is not good. (My 3 others cars pass the gadget test at idle.)
3. The car runs fine when I am driving at 2-3k RPM, but starts to idle rough and dies when parked in the driveway. (This after the Subi was jumped using a portable jumper and driven for about 15 mins. with high RPM.)

It is entirely possible that Subi needs more love, I mean driving time.
The combination of short distance local driving, less than 8 miles each way, and infrequent use, once a week, is not charging the battery enough.

I have fully charged the battery using a trickle charger, however, the burnt smell near the alternator leads me to believe the alternator is cooked.

As for the location of the voltage regulator, I need to research.

The battery is new. Got it from Costco back in Feb.
It is the burnt smell that bothers me the most.

What do you guys think?

Last edited by mikehkang; 08-08-2010 at 09:26 PM.
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Old 08-09-2010, 07:04 AM   #4
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Have you considered pulling the alternator and taking it to Autozone for a free test on their machine, which will give you a more definitive answer regarding its conditions than your gadget?

And while it's out, let it sit around for a few hours outside the car and then give it a sniff test. There could be something else in your system causing the burning smell. If it's the alternator, there could be something elsewhere in the system that's causing it to fry.

Four fried alternators in a row sounds like a Lotus (I owned one), not a Subaru.
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Old 08-09-2010, 08:24 AM   #5
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Spec info

Checked some repair specs for the 2001 Outback alternator:

(1) Voltage of the alternator output should be 13.5v at 900 rpm
(2) Current output:
18A at 1250 rpm
49A at 2500 rpm
58A at 5000 rpm
(3) Voltage Regulator:
14.3 to 14.8v at 5000rpm.

The service info also stated that the VR is part of the alternator but is a serviceable part.

HTH.

Regards,
paul...
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Old 08-09-2010, 08:46 AM   #6
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Thanks

Quote:
Originally Posted by gschotland
Have you considered pulling the alternator and taking it to Autozone for a free test on their machine, which will give you a more definitive answer regarding its conditions than your gadget?
I didn't know they did that.
I will take it to Autozone.

Thanks!
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Old 08-09-2010, 08:50 AM   #7
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Thanks

Quote:
Originally Posted by paulv
Checked some repair specs for the 2001 Outback alternator:

(1) Voltage of the alternator output should be 13.5v at 900 rpm
(2) Current output:
18A at 1250 rpm
49A at 2500 rpm
58A at 5000 rpm
(3) Voltage Regulator:
14.3 to 14.8v at 5000rpm.

The service info also stated that the VR is part of the alternator but is a serviceable part.

HTH.

Regards,
paul...
Thanks for the info Paul.
Clearly something is wrong with mine. My output is barely over 12v.
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Old 08-09-2010, 10:40 AM   #8
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Quote:
Originally Posted by mikehkang
Thanks for the info Paul.
Clearly something is wrong with mine. My output is barely over 12v.
In addition to the VR, the rectifier could be hosed causing the overall average voltage you're reading to be low.

I don't know about an 01 Outback (as I just bought an '10 Forester and it's my first Subaru), but the VR and diode rectifier for my model have separate part numbers for purchase (if you don't mind pulling the alternator apart!).

Before you tackle this job, I suggest that you take the alternator to someplace to test it (as gschotland recommended) so you don't change parts that are working fine.

Regards,
paul...
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Old 08-09-2010, 11:39 AM   #9
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Driving the car a dozen miles once a week is probably murder on your battery - depending on how much parasitic drain the car has when parked. Charging systems in cars are meant to keep the battery topped up, not charge it from near flat. I would get a battery maintainer for it.
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Old 08-09-2010, 12:11 PM   #10
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I hear you

Quote:
Originally Posted by yimmy149
Driving the car a dozen miles once a week is probably murder on your battery - depending on how much parasitic drain the car has when parked. Charging systems in cars are meant to keep the battery topped up, not charge it from near flat. I would get a battery maintainer for it.
It is unfortunate for the Subi that it has to compete with the Boxster for driving time.
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Old 08-12-2010, 01:53 PM   #11
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Final update:

I took gschotland's suggestion and took the alternator to Autozone for test.
It failed.

While I was removing the alternator, I checked the belt and it was really bad - the burning smell was coming from the alternator's pulley and the belt contact. I didn't know it at first but the black powder on the alternator's side that faces the pulley was from the belt!

The best news is that I think I discovered WHY I have had problems with my alternators. My theory is that the belt's tension was too tight. My Subi has adjustable tension bolt. I am about a good half inch lower than where it was and now the tension seems just right. (I really need a better way to tell tension. Any suggestions?) If I were to set the adjustable tension bolt to how it was, there is almost no give in the belt.

My guess is that all the previous "paid" mechanics didn't bother to really check the belt's tension but always restored to the tension bolt's previous and wrong setting.

My lession?
1. The collective knowledge of this forum is invaluable.
2. If you want the job done right, you have to do it. Or, at least you should have an idea so you would know if the job was done properly.

Thank you for all you input.

P.S. My gadget is happy too. I do get the "alternator bad" sign when I idle AND turn on the A/C, but I can live with that.

Here is the picture of my gadget.


Last edited by mikehkang; 08-12-2010 at 02:22 PM.
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