lifespan of alternator?

mike944 · Nov 2, 2006

Hey everybody,

I hardly ever hear of anyone with alternator problems. Do these cars really not have issues with this, or people just don't talk about it? Most other cars need alternators replaced somewhere between 120 - 175K

I'm trying to get an idea how long the stock VW alternator lasts in the TDI. I don't like being stranded. I would rather replace things on a "preventative" basis. I'm planning to keep my car until around 300K, when should i change the alternator? (i'd like to change it BEFORE it fails) Am i crazy for considering this?

So, who's had alternator failures, and at what mileage?

turkeyssr · Nov 2, 2006

mike944 said:
So, who's had alternator failures, and at what mileage?

No failure yet, besides the alternator pulley, but the brushes at 70k miles looked okay. I'm thinking the could last at least another 50k miles. When I get to around 120k, maybe I'll take it off and check again.

lrpavlo · Nov 2, 2006

I've replaced 2 so far....Don't remember mileage....@150K IIRC. Both were due to diode pack being bad.

mike944 · Nov 2, 2006

lrpavlo - you mean you replaced one with a bad diode pack at 150K, and the replacement also had a bad diode pack?

I have 125K on my car. No issues so far, but getting close to typical replacement intervals for most automotive alternators.

oilhammer · Nov 2, 2006

Seen more bearing and/or pulley failures than charging failures. I'd rate the Bosch unit as not quite as good as a Denso, but far better than anything GM has ever had save for some newer cars that use Bosch or Denso.

The Valeo VW alternators are not as good as the Bosch, don't really know about the Hitachis yet.

Either way, they are not a high-failure item.

ben stevens · Nov 2, 2006

pulley failure

the pulley failed at 120,000. alternator was fine and someone else is probably using it, as it was returned to bosch as a core. i would still be using it if i knew then of the ability of renewing the pulley.

TornadoRed · Nov 2, 2006

I had the alternator pulley bearings go out at 78k miles, and then the alternator itself needed to be replaced at 180k miles. I am not exactly sure what happened there -- something froze up, after some very bad noises for about five miles of driving, and I could not restart the engine. When it was all put back together, my service advisor was gone for the day, and the old alternator was not returned (core deposit). I'm just guessing that something that was supposed to rotate freely just stopped rotating.

My general opinion is that the pulley bearings are a common problem, but my other predicament with the alternator was an anomaly.

Stibz · Nov 5, 2006

My original one lasted 240k...

lrpavlo · Nov 5, 2006

mike944 said:
lrpavlo - you mean you replaced one with a bad diode pack at 150K, and the replacement also had a bad diode pack?

I have 125K on my car. No issues so far, but getting close to typical replacement intervals for most automotive alternators.

Two different TDI's have had bad diode packs. One was a 99 Beetle and one was a 99.5 Golf

kaylopt · Feb 14, 2019

2006 Jetta TDI Replaced the pulley at 140 Alternator still going at 180k - Seattle WA

TornadoRed · Feb 14, 2019

kaylopt said:
2006 Jetta TDI Replaced the pulley at 140 Alternator still going at 180k - Seattle WA

Way to revive a zombie thread that was dead for 12 years!

ItAintRodKnock · Feb 14, 2019

My first thought was, "how did this mk4 thread get so many replies before I had a chance to read it once." Then realized the date, as mentioned. ZOMBIESSSS!!

Just to add to the content, I replaced mine 30k ago, around 270,000miles is when it went out. After sitting for a year(2017) or so, then died after about 1000 miles. It would blink intermittently, then stay off for a lot of miles, then come back, it let me know it was going out.

Sent from my VS987 using Tapatalk

~TDIguy~ · Feb 15, 2019

Way to bring threads back from the dead!! Mine went maybe 20k miles ago at 150k something as i remember... Suddenly just died! I was in a crunch so i had the local shop swap it out and they took the old one for the core, so i never did find out what was wrong.. Im motoring happily along now again!

mk3 · Feb 15, 2019

I am at 308k miles with the original alternator, ! however !

I have replaced the clutched pulley - a long time ago

I replaced the brush/regulator unit 1 year ago and at this point - probably should have changed it out but I was lazy and it was cold outside : O

I replaced the wire harness just last week because a termination near the fuse box went bad (fuse did not open) and the fuse box started melting and the battery was not charging

short story - above 200k it would be wise preventive maintenance to replace the harness and the alternator with the caveat - how do you find a good replacement alternator that is not worse than the one you are removing?

ToxicDoc · Feb 15, 2019

mk3 said:
short story - above 200k it would be wise preventive maintenance to replace the harness and the alternator with the caveat - how do you find a good replacement alternator that is not worse than the one you are removing?

Maybe pull down yours and just change the brushes and clutch pulley? Those are the biggest wear items and easy to change on a bench. Then eventually once you start hearing bearing noise get a Bosch rebuilt unit.

kreibach · Feb 15, 2019

I replaced the pulley at about 200k miles and the whole alternator at 310k miles when the rear bearing shreaded. Popped a new alternator in and it's going fine at +10K. I wouldn't do it as preventative maintenance personally.

AndyBees · Feb 15, 2019

Seems the OE Alt on my 2000 Jetta made it to about 300k before having to install a new brush set (which includes the regulator)... otherwise everything else is at +370k (two pulleys, maybe on the 3rd). (son owns it now)

Fahrvegnugen · Feb 15, 2019

Replaced pulley at 150k, within 5k miles a scraping grinding metal sound I thought was the timing belt turned out to be a failing alternator. Took it out and saw the pulley still worked properly so replaced the whole thing.

Nuje · Feb 17, 2019

Just over 200K miles (310K km) on the Jetta wagon and it just locked up on me - alternator belt locked up and wouldn't allow the engine to turn over. The bad news: I was almost 10 hours from home; the good news: I was in Portland, where there's CascadeGerman.com and more than a couple gurus to help me get going again within a couple days.

(oldpoopie said the alternator was just totally frozen, like a bearing had gone bad and locked up the shaft - needed a full alternator replacement.)

On my 2002 Golf, the alternator (seemed more like the regulator, as the alternator bench-tested OK) went around the same mileage - just over 315K km.

BeetleDragon737 · Feb 20, 2019

At 177k miles, my alternator stopped charging my battery. Nothing mechanical was wrong with it, but I took it to Autozone and after testing, they confirmed the thing was totally shot.

Replaced it and everything's been great since.

Ol'Rattler · Feb 21, 2019

TornadoRed said:
Way to revive a zombie thread that was dead for 12 years!

Now it we could bring this Zombie back from the grave.

Nero Morg · Feb 21, 2019

Jus have one of them deer bite 'em

Cleenlivin · Feb 25, 2019

I had one last about 230k miles. After I replaced the pulley at 220k, the bearings finally went at 230k.

lifespan of alternator?

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