So was going down to NC from VA to see my daughter last weekend, 2.5 hr drive in the 225k mile Disco. Ultragauge alarms on low voltage about 1 hr in to the drive - middle of nowhere VA. 11.5 Volts and dropping fast. I'm turning off the hvac, radio, all electrical load but the fuel pump is still draining power. Looking for an exit, did not make it all the way up the exit - about 10 mins from the alarm to the engine being dead. Engine dies about 9.5 volts. The truck has a solar battery charger on the dash so that delayed it a bit. A good samaritan helped jump her off and got me to the end of the exit and in to an abandoned gas station.

My options at that point:

1. 1 hr tow home. Probably wait for 1hr for tow truck
2. Daughter drives me home, and I pick up spare alternator and return to disco for repair. 1.5 hr for her, 1 hr back to house, 1hr back to truck, 1.5 hr to her house. 5 hr delay
3. Daughter picks up alternator in Greensboro, brings it to me, install, carry on. 1.5hr delay

I selected #3. Autozone has it in stock. She picks it up and heads towards me.

I proceed to remove alternator and disassemble in the 1.5 hr I am waiting for her to arrive. I remove the brush holder and I can feel the brushes are worn out, at the end of their travel and no longer contacting the slip ring, no spring tension.


If only I could advance the brush holder a little bit more! But the holes are not slotted, and one end has a metal bushing in it.



It won't go in far enough to put the bolts in behind the holder.



I have an hacksaw in the truck (you never know), so I decide to slot the left side hole with a v-slot so I can rotate it in just a bit and then put the screw back in behind the V so it will trap it in place.




Put the screw back in and it holds, spring tension against the brushes now. Put it all back together and put it on the truck.

Daughter arrives 10 min later, I jump off the truck, yep its charging. Went on to NC and then drove home, so 4 hrs on modded alternator.

Pulled it off at home and swapped with the spare. You can buy replacement brush holders with burshes installed, but upon inspection there is a lot of wear on the slip ring.



Also the front bearing was not gone but you could feel wear, so it needs a complete rebuild kit. Honestly a bit involved for most folks due to the need for a press and a larger soldering iron due to the size of contacts.

For all you overlanders, if you are over 180k you are living on borrowed time. At a minimum you might want throw a spare brush holder in the truck, might even consider pro-actively replacing the alternator before you are doing a trailside repair.

Failure/Life data point - about 225k miles.

Rover on!

 

Cool fix! Hacksaw going in truck today!

 

I noticed my Disco running in the high to mid 12's under load this summer while on vacation. Ordered a new Bosch alternator as soon as I got home. Should be good for many years to come now.

 

Great hack Extinct! Literally! Lol

Last year, my alt light lit up on the dash just as I was heading out of town (crap)... I turned around and drove home and tested zero volts coming out of the alt. I pulled it apart, and was able to pull the magnets out just enough to make contact inside the alt, I also ran some scotchbrite over the slip ring area. It charged for couple months before I finally replaced the voltage regulator for 30 bucks. I didn't replace the bearings due to the pain is the AZZ feature....and they felt fine. My alt has 172,000 on it. I believe your fail rate numbers.

 

X2 on the excellent "hack"! I had the same problem driving from Boston back to Philly a few weeks ago but employed a different sort of fix. I'll add my experience for future reference. I was pulling out of a parking space and crawling across the parking lot when I noticed the battery light was on. I'm not sure when it came on or it if never went out in the 15 seconds since I had started the truck, as I was trying to navigate the parking lot and not looking at the cluster. When I noticed it I blipped the throttle and it went out. From there I drove it only short distances from the hotel to the office for two days, and never saw the light again. I set off for home on the third day and just outside of Waterbury CT, about 1.5h into the trip and still 190 miles from home (at 8pm), the light came on solid on the highway. Within a few moments of my brain going into hyderdrive and trying to assess my options given the circumstances, I was passing an exit so I dove for it and as the revs decreased and I slowed to enter the ramp the light went off. I swerved back onto the highway hoping that fortune would smile upon me but no such luck, as soon as the revs went back up the light came on again, and I was now past the exit.

I killed all the power items and drove on using only the fogs and running lights. Got off the next exit a few miles down the road and straight into a gas station. Sure enough, the meter showed 11.6 volts at the battery so I knew the alternator was failing. I shut it down and called all around but none of the usual parts stores had one in stock. The battery still showed 12v on its own so I drove about 25 minutes (20 miles) to a friend's house in North Haven CT. As I pulled onto his street the M&S started flashing and the truck went into limp mode, 3rd gear only. The battery measured 11.3 in his driveway with the truck running, not sure how much longer I could've gone but this was a safe harbor for now.

The conclusion was that since he was away on a ski trip I commandeered the keys to his Tacoma from his wife and drove the rest of the way home. In all the excursion only cost me about an hour (that's my "success story" part of the post). I was due back in Boston the following week so I grabbed two spare used alternators from the shelf and set out on a Monday afternoon. I stopped in North Haven CT, swapped the alternator and went on my way. The donor truck showed only 116k on the odo so I hope it's good for a while, the other spare is either 153k or 172k, not sure which truck it came out of but it's now in the back of the truck. Main takeaway for me was to add an alarm to the UltraBlue at 12.5V. I'm not sure if that would have saved me but mine was dying a slow-ish death so maybe that could have bought me enough time to order a spare alternator for ~$240 from a parts place (a rental car to drive home from Boston and get my spares would have been cheaper). I also wasn't aware that changing the VR was an option on these trucks but if it's easily swappable that's a lot easier to haul around in the truck for the inevitable. Is it changeable in situ or are you pulling the alternator regardless?

 

Changing the VR/brush holder and brushes requires alternator removal and removal of rear cover. I have two spares as well, one was already from a previous swap. Both had severely worn slip rings, so I think around 170-200k miles a brush holder might extend life 50-75k but I would not count on it for 150k.