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Discussion Starter #1
Hi all, and thanks for looking.

I am having trouble with my LLB losing charge in the battery. The battery and brake lights on the dash like to come on when the engine warms up, and sometimes even the ABS light. Overnight, or even a couple of hours after parking it & I may not be able to start it without a boost. :confused: The battery charges ok with my Sears charger/starter.

Advance Auto Parts hooked up their computer, and it showed both the battery and alternator were ok, BUT there was a 5.1 Amp draw on the battery with the key off and removed from the ignition! :gasp: For the time being, I disconnect the negative cable when I park. My plan is to replace the alternator, thinking that there is an electronic part that when it's hot, causes the alternator to discharge the battery. My problem is the belt tensioner.

I can't quite get a 14mm socket on the tensioner bolt (it's a little beat-up, likely from when it was in the shop), and a 15 is too big. Has anyone found a substitute, like a Harbor Freight special that can be modified?

Thanks!
 

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I don't have an answer for the rounded bolt head, but if the alternator isn't faulty, you can delay dealing with this until the real drain is corrected.

5.1 Amps? That means there's a near short, about bit more than 2 Ohms.

If you can, do some more diagnosis before replacing the alternator. See if you can borrow a DC current clamp-on ammeter. This will allow you to measure the current in individual wires; e.g., at the negative cable at the battery (to confirm the high drain, at the heavy wire going to the starter solenoid, and in the case of the alternator, at the heavy wire at its output post. If the alternator is where that high drain current is flowing, the clamp-on meter will identify it quickly.

(It might be a drain totally remote from the engine compartment -- some lighting circuits are always powered, as is the keyless entry, and a 5 Amp current is less than the rating of most fuses related to these circuits.)

In regard to alternators, it's not the same model as used on the H4, and others have found that parts store re-built alternators listed for the H6 sometimes don't work properly. That's one reason to be sure your original alternator is in fact faulty before losing it to a "core exchange".
 

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Discussion Starter #4
plain OM: I'll try to trace the drain, although I don't know anyone who has a DC clamp-on meter. The cheap clamp-on ammeters seem to be just AC, Sears has a DC model for about $100. I have a DMM that can read up to 10 Amps, but you have to put the meter in the circuit.

That's good to know about the 9/16th socket and Irwin, thanks CNY Dave.
 

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The easiest way to track down a current draw is to take a standard multimeter that has a current setting. Remove the negative battery cable, then attach the red lead of the meter to the negative battery terminal and the black lead to the removed negative battery cable. You are basically placing the meter in series with the battery and ground. You should immediately see current draw on the meter, if not, then reverse the leads. Once the meter shows the current draw, start pulling fuses one at a time while watching the meter. If you pull a fuse and the current draw stops, then you know which circuit to investigate. Replace each fuse as you go if it does not show current draw. If you pull all of the fuses and nothing has changed on the meter, then the only things left in the circuit is the battery, alternator, starter, and associated cables.

However, with 5.1 amps of draw (which is a lot), I suspect that one of the diodes in the rectifier circuit in the alternator has shorted.
 

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Ok. After running the engine up to operating temp (and the battery light/brake warning light came on), I shut it down, hooked the DMM in series between the negative battery post and cable, set at the 10A DC setting, and red probe in the 10A socket. The meter started reading, then quickly dropped to zero. Waited a bit, no change. Opened the DMM case, and the 10A fuse had blown in two places! I then disconnected the alternator at the main post (heavy cable), put a new fuse in the DMM, and tried again. With the key out of the ignition, there was a very small current reading at the 10A setting (.001). If I open the door (dome light comes on), the reading goes to 0.07-0.08. I reconnected the main cable to the alternator, and it's the same - very low drain (I think that disconnecting the cable reset something). Next test - connect the volt meter to the battery terminals before and during running the engine. Before starting, the reading was 12.6-12.7 volts. Start, and running, the reading is 13.2-13.6 volts. At this point, the battery light is off. But after running for a few minutes, with A/C, headlights, fog lights all on, there is a "click" from the alternator, the battery and brake warning lights come on, and the voltage drops to 10.5 (A/C on, lights off), then all the way down to 9.1 volts with the A/C and lights on (engine running rough, too). I can rev up to 1500 RPM (but the engine really struggles at this point) and get the voltage up to 10.5-11 or so, but it quickly drops back to less than 10v at idle (~800 RPM). I am pretty sure I need a new alternator.

Question now is, which alternator? Is one re-manufactured one better than another? Advance has a "Worldwide" Alternator for $124+core, and a Beck-Arnley for $240+core. Does anyone have experience with these brands? Another thread mentioned a new alt from Remy, but I checked and all they had on their eCatalog was a reman (same catalog number as the Worldwide that Advance has, #12289!)
 

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Ok. After running the engine up to operating temp (and the battery light/brake warning light came on), I shut it down, hooked the DMM in series between the negative battery post and cable, set at the 10A DC setting, and red probe in the 10A socket. The meter started reading, then quickly dropped to zero. Waited a bit, no change. Opened the DMM case, and the 10A fuse had blown in two places! I then disconnected the alternator at the main post (heavy cable), put a new fuse in the DMM, and tried again. With the key out of the ignition, there was a very small current reading at the 10A setting (.001). If I open the door (dome light comes on), the reading goes to 0.07-0.08. I reconnected the main cable to the alternator, and it's the same - very low drain (I think that disconnecting the cable reset something). Next test - connect the volt meter to the battery terminals before and during running the engine. Before starting, the reading was 12.6-12.7 volts. Start, and running, the reading is 13.2-13.6 volts. At this point, the battery light is off. But after running for a few minutes, with A/C, headlights, fog lights all on, there is a "click" from the alternator, the battery and brake warning lights come on, and the voltage drops to 10.5 (A/C on, lights off), then all the way down to 9.1 volts with the A/C and lights on (engine running rough, too). I can rev up to 1500 RPM (but the engine really struggles at this point) and get the voltage up to 10.5-11 or so, but it quickly drops back to less than 10v at idle (~800 RPM). I am pretty sure I need a new alternator.

Question now is, which alternator? Is one re-manufactured one better than another? Advance has a "Worldwide" Alternator for $124+core, and a Beck-Arnley for $240+core. Does anyone have experience with these brands? Another thread mentioned a new alt from Remy, but I checked and all they had on their eCatalog was a reman (same catalog number as the Worldwide that Advance has, #12289!)
I dunno about fitting a newer H6, but someone has posted a number for dealer rebuilt Alt. with a very nice price.

anyone have details?
 

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Discussion Starter #8
Pulled the alternator this morning. Not too difficult, except for the serpentine belt. I could not get the tensioner to turn properly, and ended up removing it. Found out then I have the wrong size belt! It's marked 6PK1625 / 640K6, looked it up and that means the belt is 1625 mm (64") long. A couple of on-line sources say I need a 6PK1640 belt, that is (of course) 1640 mm (64.5") long. Running since I bought the car in January with a belt that's too small.

The alt is marked Mitsubishi R 23700, AA401, LSC, A3TB1891 0Z06. I will be dropping that off at Texas Alternators in north Austin on Monday, and they will see what needs replacing. They also said they could order a new alternator from WAI. Made in China, about $250. I plan on sticking with the Mitsu if it can be rebuild at a reasonible cost.

Thanks again for the help!
 

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The alternator on the H6 cars is regulated by the ECM, not a regulator within the alternator. You may also want to check all the ground anchors, especially the ones coming from the engine harness. Lack of good grounding will make an alternator and all other electricals act up, especially if the ground feed to the ECM is weak.

There is a ground on the block by the starter, 2 on the passenger side of the intake manifold, one on the body by the battery, on the body at the firewall next to the brake booster, 2 cables on either side that bolt to the injector covers and a couple smaller ones that run from the block to the body depending on the options on the car.
 

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The alternator on the H6 cars is regulated by the ECM, not a regulator within the alternator.

This is a first for me. I have never heard of a car that did not have a regulator/rectifier built into the alternator, except pre 70s cars which had a separate regulator external to the alternator. I checked several parts outlets and they all list a regulator for the H6 alternator. I am not saying that you are wrong, and I fully acknowledge that you have way more experience with Subarus, but I have to question this comment.
 

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This is a first for me. I have never heard of a car that did not have a regulator/rectifier built into the alternator, except pre 70s cars which had a separate regulator external to the alternator. I checked several parts outlets and they all list a regulator for the H6 alternator. I am not saying that you are wrong, and I fully acknowledge that you have way more experience with Subarus, but I have to question this comment.
The ECM regulates the alternator based on necessary load and what you are doing with the car, i.e. passing, it lowers the alt output to reduce engine load if you floor it. The H6 is not regulated in the normal manner that all the other alternators are.

Pookie2 had issue with his H6. Thread can be seen here:

http://www.subaruoutback.org/forums/110-gen-2-2000-2004/47323-dont-tell-me-these-things-dont-have-feelings.html
 

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Cardoc,

Thanks for the additional info. I think this is just me misunderstanding the terminology being used. My understanding is that the ECM does indeed regulate the output of the alternator, but it is the alternator that is outputting DC voltage. An alternator cannot output DC voltage unless there is an internal rectifier unit. The term regulator (part # 23815AA160) is used, but it is in fact a rectifier. So basically, the ECM monitors the DC output and sends a signal to this internal regulator to increase or decrease output depending on load.

Of course, I could be totally out to lunch.
 

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Based in part on our discussions in the linked thread, I suspect the Subaru H6 alternator does have an internal regulator that is designed to monitor the voltage in the system, more specifically from the battery (the blue/red connection off pin 2 in the wiring diagram), and maintain the alternator output at it's design level (e.g. ~14 Volts).

In the case of the H6, however, as cardoc noted, the ECM has that extra connection (pin 3) that enables it to override the internal regulator, as might be the case when the engine is under heavy load, or perhaps when the drain on the battery isn't great (cruising without accessories, AC, or radiator fans on) thereby reducing fuel consumption. I also suspect that the regulators inside those replacement/rebuilt alternators (linked thread) were either the wrong ones or were defective.

Incidentally, although the 2.5 doesn't seem to have this "feature", the alternator connector, at least on my 07, has three pins and three wires going out into the engine wiring harness. I wonder why Subaru would include that third wire when, presumably, it has no function.]
 

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Discussion Starter #14 (Edited)
Ok, to wrap up this thread (Thanks again for all the help!) I installed my old alternator, rebuilt by Texas Alternator & Starter ($131 to replace the regulator and bearings, 2 day turnaround). I replaced the tensioner & idler bearings too, and used the new 1640 belt. Getting the belt on was still a bit of a bear, but by using the slack in the alternator mount it all came together. Started right up, and ran it until it got to operating temperature. With all the lights on, A/C, radio, etc., it still was putting out 12.8 volts! About 14.7 volts with all that stuff turned off, engine at idle. I think this fixed the problem! Now about that pesky oil leak at the rear...

Edit: All that, and I forgot about the title of the posting! Yes, I used a couple of items from Harbor Freight as my "tensioner tool". I bought their offset wrench set, #32042 for $15.99, and their "dogbone" wrench, #65497 on sale for $9.99. I used the offset wrench mostly, but it did slip off occasionally (it's a 12-point). The dogbone, having a six-point socket, seemed to hold better.
 
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