[bshusted]

My wife's 01 VDC has started to make a high-pitched "whine", especially starting from cold. Being the original alternator a1 170k miles I suspected it. With the engine running, I touched my screw driver (stethescope) to the case of the alternator, PS pump and AC compressor. The PS and AC were quiet, but the noise was obviously from the alternator.

I found a local alternator re-builder (reputable place) and brought it to him. On his test stand, he could only making it "whine" by putting a load greater than 60A on it. Otherwise, he thought that the alternator was fine. There should not be a 60A load at idle. He suggested that the battery may be the problem.

The battery is getting up there in age, but the car starts right up even in the 25F weather we've been having recently. I'm wondering if it is less the problem of the battery and more the cables going from battery to alternator. I've cleaned the battery terminals, with no change in the sound.

I did also replace the idler and tensioner pulleys with no change in sound, though the old ones seemed a little sloppier than the new.

Thoughts?

 

[1 Lucky Texan]

not very helpful thoughts but, bad cables would limit current flow, and probably be very hot at 60 amps continuous.

here batteries are old at 3 years, even in cooler temp locales, batteries are 'getting' old at 4-5 years so, might be worth having it tested. If they've ever had a total discharge or 2, the lifespan is cut even more.

while idling, look in the power steering reservoir for bubbles/foam.

 

[CNY_Dave]

My H6 alternator (they are different from the H4s, the H6s are controlled by the computer) is still quiet at 200k, at least i consider it quiet. There is a little noise from up front.

I would say if worried, just have a rebuilder toss new bearings in it.

In fact, since it is controlled by the ECU, I wonder how he bench-tested it? He must have a pretty complete setup.

Also, the bearing load from the belt in the car might be considerably higher than the load on his test stand.

 

[bshusted]

I've already looked at the PS pump, etc. for leaks. I'm confident that the PS is not the problem.

Since the battery seems to have no problem starting the engine, I'm assuming it is not the issue. I may try swapping the battery from my other car in, just to see if it makes a difference.

I don't think that the H6 alternator is actually "controlled" by the ECU. The voltage regulator is internal to the alternator. The only influence that the ECU has is that the alternator is shut down when at wide open throttle by grounding the 3rd pin on the alternator plug. Other than this, I find it hard to believe that the ECU has any other influence.

I had thought about the side loads created by the belt, but thought that the rubber wheel against the pulley to spin it would create enough of a side load to simulate the belt.

 

[CNY_Dave]

It could be the WFO cutout is the extent of the ECO control I just know it's been stated here the ECU has some degree of control.

My guess would be the rubber wheel might exert far less force than the belt in the car.

You might even be able to google up the bearing sizes and DIY the replacement.

 

[bshusted]

Update: I decided to run the engine with the serpentine off, just to be sure that the noise was one of the accessories rather than something internal. No noise.

I reattached the serpentine and then removed the electrical connections from the alternator. No Noise. The bearings are silent. The voltage drop from the alternator to the battery is only a couple hundredths of a volt (possibly meter error). I may try to add an additional ground to the alternator case to see if it stops the sound.

 

[bshusted]

Update #2: I've swapped the battery with the one from my other car and had no change. I'm not sure what else to test. All signs point to the alternator, but it "tests" good.

 

[John E Davies]

Update #2: I've swapped the battery with the one from my other car and had no change. I'm not sure what else to test. All signs point to the alternator, but it "tests" good.

.

If you have eliminated all the other possibilities, then put a new alternator on the car. Be VERY wary of rebuilt units, especially cheap ones.

John Davies
Spokane AA USA

 

[bshusted]

I don't want to go down the road of reman alternators, which is why I found a local shop that rebuilds my core with OEM parts. When I took it to them though, they said it was fine. Maybe I should just have them rebuild it anyway, but there is no guarantee that it will stop the noise. It's amazing that it can be quiet mechanically, but shriek like that when the field is excited.

Anyone in the Seattle area want to loan me their H6 alternator to test if it stops the noise?

 

[1 Lucky Texan]

very thorough troubleshooting.

sucks to need an alt, but at least you weren't stranded by it.

 

[bshusted]

So, I've been looking for alternators now. How does one find a "good" replacement as most reman units are trash? None of the local junkyards seem to have H6 alternators.

 

[CNY_Dave]

Car-Part.com--Used Auto Parts Market

Looks to be a number w/in 50 miles of redmond.

 

[bshusted]

Both of those junkyards require a ferry ride (major pain) and are asking over $100 for an alternator with no warranty.

 

[CNY_Dave]

Most of those junkyards will ship, but yeah, few with a warranty.

 

[CNY_Dave]

Some info on this critter, and the role of the ECU:
http://www.subaruoutback.org/forums...onics/38827-advice-auto-electrical-gurus.html

 

[CNY_Dave]

100 bucks after core and before shipping:
2001-2005 SUBARU OUTBACK 3.0L ALTERNATOR 13888 A3TB1891 - MITSUBISHI REBUILT ALTERNATOR

 

[bshusted]

Thanks!

 

[bshusted]

So, I got another alternator and installed today. Here is the kicker...it still whines! The replacement alternator exhibits the exact same symptoms as the original one, so I am starting to believe the alternator guy that said mine is good.

What else can it be??? This cannot be a "normal" noise. There are actually quite a few H6 Outbacks I've seen in the Seattle area and none of them sound like this.

 

[1 Lucky Texan]

I know you said you had no leaks, but did you look inside the ps reservoir for bubbles/foam while idling?

 

[bshusted]

I'm certain that the PS pump is not the cause of the noise. Running the engine with the charging cable removed from the alternator makes everything go silent. I appreciate the thought though. Others?