Help! Battery light on, alternator failure on cross country trip.

[slam]

Need a little help from the forums this week. I've driving cross-country trailing a motorcycle and I've hit a bit of a snag.

Battery light started flickering this morning at 65 mph+. At first it would stop flickering if I released the accelerator, but in an hour it was solid at 65 mph+, and by evening it's solid at all speeds.

Pulled into an Autozone, checked my battery, it's fine. Bought a multimeter and I get 12.5V when off, 12.4V when running, both checked at the battery. I also checked power from the alternator positive terminal to the alternator body and it shows 12.4V.

Alternator belt was literally done just before this trip. Brand new, it doesn't appear to be slipping. Tension is good.

I can pull the alternator and test it at Autozone but I have limited tools on the road.

Two questions:

Have I ruled everything out but the alternator itself?

And if I do replace to the alternator, do I need to replace it with a 120A or will the 90A do? The smaller one is in stock; the larger will take two days to arrive leaving me stranded in Michigan City, MI, on my way to California.

Thanks folks,
Scott

 

[ToddA1]

My bet is the voltage regulator, under the black cover. Easy to swap.

-Todd

 

[slam]

I thought they were built-in on this model. If I can swap it that would be awesome. I am not looking forward to arm-wrestling the tensioner.

 

[ToddA1]

2 screws hold it on. It's easier to do off the car, but it's possible on the car.

-Todd

 

[TonyJetta]

If you can find the regulator module in your locale, it's a pretty straightforward field replacement. BTW...the regulator module contains the brushes, too.

I don't have a PN off hand. Napa may be of some help.

Tony

 

[slam]

My alternator has the black cap, so it appears to have the separate voltage regulator as well. I can at least pull it and check the brush wear.

How to determine if the failure is in the alternator vs the regulator? The regular is actually more expensive at Autozone.

 

[Vince Waldon]

Hard to do without special test gear....but if you are saying an alternator is cheaper than the regulator run and get the alternator, since it will contain a brand new regulator as well.

 

[slam]

If I pull the alternator and take it to Autozone, can they determine whether the alternator or regulator failed?<br> <br>

 

[Abacus]

Odds are very good it's just the voltage regulator, Bosch part number 1197311530.

But find an independent shop, they may be able to just replace the brushes, which I'll bet have worn down. My rebuilder did this last time since his source was out of the regulators. I keep one on hand just in case. The regulator can be replaced on the car but as Todd says, it's easier off the car.

If sourcing one is difficult or too costly, head to a junkyard and pull an alternator off a car of the same vintage, even if it's 90A. It'll work fine and will give you time to have yours rebuilt. I would not recommend using yours as a core for some parts house alternator, even with a 'lifetime' warranty. I did that once and never again.

 

[Vince Waldon]

The regulator's connections are inside the alternator, so difficult to test by anyone... but the good news is that it's solid state and almost never fails.

Far more common is worn brushes, as posted above... which is part of the same assembly. If the brushes are worn it's worth checking for slip ring wear as well... no sense wearing down new brushes on an alternator that needs a full overhaul/replacement.

 

[TonyJetta]

Maybe...depends on who runs the machine.

The regulator assy contains 90% of the electronics involved. 90% of the failures in these alternators is the regulator assy. Not to mention a new regulator assy means a fresh set of brushes. Beyond the bearings, that's the other wear item in these alternators.

If you want to throw a cheap alternator at it, buy a VR6 or 90A alternator at O's or AZ, and move on.

Tony

 

[slam]

It looks like Autozone has the complete alternator assembly with regulator for $130 or so. They have the voltage regulator alone for $179.

My mechanic, Mike from Left Lane Cars, suggests that on original alternators it's really easy to spin a particular stud when trying to bust the regulator nut.

Mike also suggests there's very little reason to get the 120A vs the 90A alternator. It's not like I run a lot of accessories. Just my phone charger and trailer lights.

Or if I go regulator alone, AutohauzAZ has the regulator for $52, can anyone suggest a local (Chicago area, not AZ) source for that?

 

[Abacus]

I have yet to see the stud spin on an alternator and I live in the rust belt capitol. You can get away with running a 90A alternator, my younger brother did it on tacsat's old B4, but it was screaming this past winter, even with the Frostheater. The larger alternator is not for your accessories, it's for the ones built into the car, like the coolant glow plugs, which suck up a lot of juice.

I did the swap route years ago and that alternator failed about every year, so make sure you keep the receipts. The last time I brought it in to Autozone, they said it'd take a week to get one. When I complained they upgraded me to a Bosch that has been fine ever since. Carquest did the same thing with my starter, and I learned my lesson on both. If it's not a Bosch, don't bother.

But you need something now, not later. Do what you must since you're on the road and need to continue your journey. I'm just relaying my experience with big parts store electrical parts.

 

[artie b]

Where are you Slam? Which way are you headed, East or West? You mentioned Michigan City, in the state of Michigan. There is a Michigan City, in Indiana. I may be able to help, in some way, if Indiana. PM, with a phone number, and location, if Indiana, Artie

 

[tdidieselbobny]

Go ahead and buy the 90A alternator,but keep the core. That way you can motor on,have a "lifetime" warranty one and you can get a regulator and put it in your old alternator when you get back home. I found a regulator on ebay for under $30 and put that in my original 120A alternator,so I can put that back in car-the 90A one I bought a couple years ago is giving wonky voltage readings on the scangauge-sometimes 13.1-13.3,then 13.6-13.9.

 

[slam]

Hey folks,

Thanks for the help. I opted for the 90A rebuilt Bosch. Swap was easy; I used a $12 ball joint spread fork to grab the tensioner arm, pull it back, and ziptied the fork down so the arm stayed out of my way.

Pulled the 120A stock unit and examined it; the copper contacts on the hub were grooved about 1/4" deep. Sadly I gave it up as a core; didn't consider that I might rebuild it myself later.

(Can't seem to embed images, here's links)

https://www.flickr.com/photos/slam-pics/21283486469
https://www.flickr.com/photos/slam-pics/21470290275
https://www.flickr.com/photos/slam-pics/21459368552

 

[TonyJetta]

Yes, that slip ring is pretty much worn out. You might have been able to have it turned, but I doubt there would be a long life left.

Tony

 

[KLXD]

Haven't I seen, on these very Forums, a thread about replacing the slip rings?

I ask because my light just came on tonight after 330k.

 

[Abacus]

Yes, TDIDaveNH posted it awhile ago.

 

[slam]

330k is almost exactly my mileage, too.

Kicking myself for returning the 120A as core now. Would have loved to rebuilt it instead!

 

[KLXD]

I intended to buy the parts to be ready for this or maybe do it proactively. I guess it couldn't wait any longer.

 

[KLXD]

I pulled out the regulator. Slip rings and brushes were pretty worn, inner brush was no longer making good contact.

I pulled it out to stretch the wire inside that would have spent years bunched up and pushed the whole assembly in toward the shaft when tightening the screws.

It's charging again. Hopefully it'll last for my 150 mile trip and back while I order the brushes and rings. Bearings too maybe though I hate to replace good bearings; even with over 300k.

I measured the current draw at under six amps with the lights off so I should be ok for a 2-1/2 trip if it doesn't hold up. Maybe I'll take one of the batteries out of the Dodge to bring along just in case.

 

[Digital Corpus]

The hardest part about the slip ring is installing the new one without damaging it. Need to do a tutorial about the whole process one day. I am usually on a boring and relaxing vacation in December over New Years. I'll probably do the whole tutorial session then and beef up both alternators if I manage to get the larger bearing free...

 

[tdidieselbobny]

On the 120a alternator I'm going to be re-installing, the slip ring is smooth on the top,but it has a groove on the lower part for bottom contact of the voltage regulator. It tested good on the machine at Advance,so not sure how much life it will have-I'd guess the groove is about a 1/16" deep,not as bad as the one in the pic in the above post.I ordered a clutch pulley,not a Gates,so I guess I'll be the test car for it-it was off ebay,from a "TrueBlueAutoParts",for $44.95 + tax(thanks,NYS).

 

[Abacus]

W386 bought the same one from the same person to replace the Gates he used. There are no indicators that it's a Gates like they say it is but all the numbers on the package cross over to a Gates. There are no identifying marks on the pulley itself but the bag it's in is sealed.

I have not installed it since it's a spare sitting in the garage in case its needed. Time will tell I guess.

 

[tdidieselbobny]

The one I bought wasn't advertised as a Gates,but the pic shows the # 37010PX-they also had a different auction for a "Gates" pulley,but it was $53.95.