98 Outback. Is my alternator going?

[jimkasper]

1998 Outback, 50,100 miles.

I inadvertently left the drivers door ajar for two days and completely drained my three year old battery.

After a jump, the AAA guy said it might not hold a charge, so I elected to replace it.

 

At the station, (not my regular mechanic) a load test showed the alternator putting out 12.9 volts(?) at idle and 13.7-13.9 when the engine was revved. He recommended a new alternator.

 

Are my voltage levels much below specs?

I am going to get it checked by my regular mechanic at my scheduled oil change next week. If the alternator needs to be replaced, would a rebuilt unit be OK or are the Subaru units superior.

 

Thanks,

Jim Kasper

[BigMattyD]

As far as I can remember, I think 13.8 volts is the normal regulated output for the system. I know that automobile electronic equipment (CB's, scanners, radios) are designed to work at 13.8 volts.

 

 

If your charging system light on the dashboard is not illuminated, I would leave it alone. I think the guy is just trying to make some extra money off you.

 

Matt D.

 

P.S. I just replaced my alternator because it failed. There were no early warning signs.

 

A rebuilt OEM Subaru alternator from 1stsubaruparts.com was $67.50. At my local parts stores it was about $120 for a generic rebuilt. A brand new one is about $225.

[deiscient]

At the station, (not my regular mechanic) a load test showed the alternator putting out 12.9 volts(?) at idle and 13.7-13.9 when the engine was revved. He recommended a new alternator.

According to this page the alternator ranges for a 93 Legacy should be 13.5 and 14.3-14.8 V, respectively. Granted, the spec. may be different for your later model than for mine. Nevertheless, at first glance your mechanic may be correct to raise a flag although your car may continue to operate fine at those output levels. So things are deteriorating and it will fail once the output gets below a certain threshold voltage.

P.S. I just replaced my alternator because it failed. There were no early warning signs.

Falling voltage output is a warning sign of a failing alternator. You will never sense it unless you check it with a voltmeter, however. As the output continues to fall it will eventually go below the threshold of the vehicle's electric system yielding insufficient charging to replace electric power consumption. That is when you will experience "failure". It is a process, not an event.

[Scottbaru]

Are his brushes replaceable?

[frag]

Are his brushes replaceable?

 

Yes, but it's rarely the main problem with a failing alt. It's the voltage regulator or the rectifier's diodes that go. I replaced mine with a rebuilt OEM alt from 1stsubaruparts as preventive maintenance after ten years of loyal service, and since retrurning the core was too costly to be worth the trouble, I kept the old one and dismantled it. The brushes still had a lot of life in them.

[outback_97]

Jim:

 

Have you checked to see if it's covered by a recall? My '97 was when it failed at around 60K miles. Not sure if the 98's had the same recall though. I don't know what the voltage #'s are supposed to be but when mine went out the dash light came on, also illuminated the brake light, I guess 'cause they're right next to each other?

 

Steve

 

EDIT: Answered my own question... google'd "alternator recall subaru legacy", this is from the first link:

 

1998 Subaru Legacy Outback NHTSA Recall ID Number: 00I002000

Recall Date: MAY 15, 2000

Component: ELECTRICAL SYSTEM:ALTERNATOR/GENERATOR/REGULATOR

Potential Units Affected: 223520

Summary: THIS IS NOT A SAFETY RECALL IN ACCORDANCE WITH THE SAFETY ACT. HOWEVER, IT IS DEEMED A SAFETY IMPROVEMENT CAMPAIGN BY THE AGENCY. VEHICLE DESCRIPTION: PASSENGER VEHICLES. SOME OF THESE VEHICLES HAVE AN ALTERNATOR PROBLEM THAT CAN RESULT IN A LOSS OF CHARGING CAPABILITY.

Consequence: IF THE ALTERNATOR FAILS, THE ALTERNATOR WARNING TELLTALE WILL ALERT THE DRIVER TO THE PROBLEM, GIVING AMPLE OPPORTUNITY TO SEEK REPAIR BEFORE A LOSS OF BATTERY POWER, WHICH, IF THE WARNING WERE IGNORED, COULD ULTIMATELY RESULT IN A LOSS OF VEHICLE POWER (ENGINE STALL).

Remedy: DEALERS WILL REPLACE THE ALTERNATOR WITH A MODIFIED ALTERNATOR. OWNERS WILL ALSO BE CAUTIONED THAT, SHOULD THE ALTERNATOR TELLTALE WARNING LAMP ILLUMINATE, THEY MUST SEEK IMMEDIATE REPAIR TO AVOID THE EVENTUAL LOSS OF ELECTRICAL POWER, WHICH COULD RESULT IN AN ENGINE STALL.

Notes: SUBARU OF AMERICA, INC.,

[vic/se]

1998 Outback, 50,100 miles.

I inadvertently left the drivers door ajar for two days and completely drained my three year old battery.

After a jump, the AAA guy said it might not hold a charge, so I elected to replace it.

 

At the station, (not my regular mechanic) a load test showed the alternator putting out 12.9 volts(?) at idle and 13.7-13.9 when the engine was revved. He recommended a new alternator.

 

Are my voltage levels much below specs?

I am going to get it checked by my regular mechanic at my scheduled oil change next week. If the alternator needs to be replaced, would a rebuilt unit be OK or are the Subaru units superior.

 

Thanks,

Jim Kasper

I would't touch the alternator!!!! An alternator that overcharges will boil your battery ( battery life will be short)

[cookie]

Unless you just want to change it for preventitive maintence. If it keeps the battery chanrged I would not worry about it at that level. My BMW has a volt meter and that's exactly where it runs. If you go much over that the battery will boil on a trip.

[Cougar]

It would be good to know how much load there was when the voltage measurements were taken. One of the diodes in the alternator may be out but you shouldn't have any trouble with those voltages. Be sure to check out the Subaru replacement offer if you do decided to replace it.

[shimonmor]

A simple test to see if a diode failed closed is to set your multi-meter to AC volts and measure at the alternator positive output post (AC ripple test). You should see less than 1 volt AC. If you see more...then you have a bad diode and should have the diode pack replaced or get a new alternator. AC voltage to a battery is bad because it heats up the battery and the more AC you put out, the less DC you have for actual charging. Of course, diodes can fail closed or open.

[Juan]

The '98s all had alternator recalled. I became aware of this when alternator started grindind 20 days outside of 3-year warranty. Dealer wanted to charge me for it. I stood my ground and service made some "phone calls". Service came back and said they got the "go-ahead" to replace it for free. He knew all the time there was a recall out on it.

 

I am surprised you didn't blow the computer or something when you jumped it. I hit the "virgin" switch on top of the steering column and drained the battery. I charged it overnight and it wouldn't even idle the next day. Flat-bed tow, three days in the shop (charged me for cleaning the injectors and replacing sparkplug wires) and they had it nailed down to a blown computer.

 

Surprising enough, the $600 computer was still under 6-year 60,000 mile warranty. Maybe standing my ground on the alternator flagged my service record and they didn't want to mess around. Or maybe, because of that "flag", they just wanted to soak me for injector cleaning, plug wires and three days without my car. Go figure.

 

Still, I should have pressed them for towing bill ($75).

 

Juan

[jimkasper]

I got my Outback in to my regaular mechanic for an inspection and a Mobil One oil change yesterday (I can almost hear that boxer thanking me for the new Mobil One as I drive on down the road.)

My mechanic did a load test on the alternator and said it was coming up about 14, and all is well. I guess I was being set up for a new alternator when I bought the battery.

The alternator was originally a recall item, but was taken care of by the first owner.

Thanks for all your replies and suggestions.

Jim Kasper

[m1super90]

I've read all about the Legacy alternator recall for late 90's years but I've seen nothing at all about '97 Impreza Outback alternator failures. This happened to me 2 years ago with exactly the same symptoms as reported on Legacy's. However, my mechanic, friends, nor online groups seem to ever mention my car having this failure. Well, it's happening again! Voltage drops to just over 12 and the charge and brake lights may come on. If they do, it's always simultaneously. Last time, the battery was drained dead via night time driving w/o the charge light ever coming on. Scary! Generally, starting cold results in good charge voltages. A few minutes of driving and the problems start: blower slows down, lights flicker, and charge and brake light sometimes comes on.

 

My question is, has anyone seen the famed Legacy alternator failure in an Impreza? Also, this all happened after moving to Central Texas. Is it the heat and/or combined A/C loads that's doing it?

 

I don't mind replacing the alternator but I want to be sure it's the problem. I somewhat suspect the feedback line (3rd wire). Any thoughts on that?

[Cougar]

You may be correct about the field wire being the problem. The charging light is usually in series with the field wire and if it doesn't work then the charging will stop. I assume the light works ok when you turn the key from off to on with all the other dash lights on. There may be an intermittent problem. I would pull off the road the next to this happens and stop the engine. Then then the key to on and see if the light works then. The voltage on the lead should be close to the battery voltage if things are good.

[m1super90]

Thanks Cougar. This morning...

 

I turned the key to run w/o starting. The warning lamp was on.

 

Using test leads I connected the field wire blade to the positive pole of the battery and broke the connection with the warming lamp. Upon cold start the alternator does not charge for one minute. After 3 minutes it wildly fluctuates between 14.7 and 15.8v. It makes sounds I've never heard from a healthy alternator before. After 5 minutes it quits charging again, for good.

 

Turned the motor off and the key to run. Monitoring my test connection's voltage, I broke the connection and saw no increase in voltage. Indicating no current draw. I reconnected the charge warning lamp and it was not lit.

 

With the field wire essentially connected to the alternator's output terminal via the battery, the feedback circuit must be fine. Also, after failure, it does not draw current through the field wire.

 

Sounds like a problem internal to the alternator to me. What do you think?

[Cougar]

Yes, I agree. It sounds like the internal regulator is having some trouble. If you can get a Bosch rebuild I think you will be happy with it. They have a good warranty.

[m1super90]

I may as well just change the regulator myself. Anyone know where I can get the part? (1997 Impreza 2.2L)

 

Looking at the diagram for the Delco 10SI alternator, it shows a field wire and a sensing wire. This makes me wonder what the other blade is for on my unit. Looks like two pretty heavy gauge wires. I'm using a Legacy manual by Chilton (figure it's similar enough) and it diagrams out to that line going to the ignition coil. Any idea why they do this instead of running it from the battery?