Alternator/Pulley Lifespan?

[Justin Rizzo]

I replaced my belt and alternator (Valeo) exactly 5 years ago and 40k miles ago.

My batt light is chirping on infrequently. Goes away when I apply throttle.

I'm not sure how to discern if it's my alternator or pulley that is failing, other than testing that the pulley only spins in one direction.

How long are ya'll getting on these? 5 year does not seem very long.

 

[Genesis]

2003, on the second one (original + 1 change) current one is still chooching along. ~300k miles.

 

[Justin Rizzo]

What's weird is the dash batt light goes off when I apply throttle, but the volts on my meter do not increase. They stay in the low 11 range.

 

[Gruni14]

Check the ribs to see if they're sharp. That could be a worn pulley ...meaning the belt is slipping. A good pulley will have a short flat spot on the top of each rib.

Some pulley clutches last a long time, I've had one which crapped out in 6 months. Put a multimeter on your battery cables to see what it's putting out. have someone give it some throttle.

Jetta should be nominated as "least fun alternator to replace" award!!

 

[Vince Waldon]

Well, they call it an "idiot light" and sometimes with good reason.

Your voltmeter is telling you the true story..if it's staying at 11 volts the pulley or brushes are completely gone, and the pulley spin test will help you narrow it down.

 

[Mozambiquer]

I replaced my belt and alternator (Valeo) exactly 5 years ago and 40k miles ago.

My batt light is chirping on infrequently. Goes away when I apply throttle.

I'm not sure how to discern if it's my alternator or pulley that is failing, other than testing that the pulley only spins in one direction.

How long are ya'll getting on these? 5 year does not seem very long.

Check the battery fuse block. Sounds like it may be melted.
As far as the alternator clutch pulley, I change them every timing belt on every car. Only using OEM ones.

 

[P2B]

As far as the alternator clutch pulley, I change them every timing belt on every car. Only using OEM ones.

This. They usually last one TB interval, rarely two. I do the idler pulley as well.

 

[Justin Rizzo]

Big fuses above battery are in tact. Pulley only spins in one direction, so it should be good. Exciter wire getting 12V with key set to ON. What's the other wire in that plug do? It's also getting 12V. I assumed it was ground, but I appear to be wrong.

I pulled the battery off the car and it took almost 24 hours to fully charge on my 2A charger. I'm getting 12.5V with car off, same with car on, but now I'm getting a touch more volts when I rev. Still not even 13, though. Getting nothing from alt stud to ground.

Should I consider replacing the regulator or the whole alternator. 5 years seems like trash to me. I won't be using Valeo again. Looks like I paid $260 for that in 2020 and it's now about $100 more.

 

[Genesis]

Yeah you're not charging; the most-likely reason is the alternator or regulator is toofed if the pulley only goes one way -- and typically, when they're intermittent they start making a lot of noise too.

But DO check the large wire from the alternator to the battery for damage or crunchies; if it, or the grounding (or the large terminal for it on the big fuse block on top of the battery) are high-resistance it will not charge either.

I'd call that service life trash if the alternator is actually dead.... the one in the car my daughter has is OE and has roughly 300,000 miles on it (Bosch of course) -- still works just fine.

 

[Gruni14]

Tough call.

Sometimes it pays to shop local. Autozone has limited lifetime warranty, which means, as I understand it, they "can" refuse warranty after a few years. BUT ....that said, they warranted the alternator I bought from them 2 times over the last 12 years. Meaning, I'm on the 3r one! LOL. I had to have a discussion with the manager, and I purposefully went to a store in a smaller town near me. It wasn't an argument really. She was rather nice and once she did some digging and found my original purchase, she went ahead and ordered what I needed. I DO buy a fair amt of alternators and starters from Autozone. The gal probably saw I buy a good amt of stuff from them, esp electrical parts. That may have been why ...IDK. But no way a new pimply kid would have been able to figure out what she did. So you should take to the mgr when doing something like that. Both Autozone starter and alternator were Bosch rebuilds (Mexico). I will say, each time was for something different. First was the alt clutch. 2nd time the bearing went bad and it locked up.

They also warranted the starter I bought from them 2 times in the last 10-ish years! First one lasted about 8yrs. It was the starter drive that was skipping/going out. Second time after I installed the replacement, the front drive bearing spit out after about a month. The one I have now has been on there since last fall ...seems good (knock on wood!!). Hard to say if I bought them from somewhere else...would they have been any better rebuilds?? Probably not. Autozone probably buys from the same places the RockAuto rebuilds come from.

I often rebuild my own starters and alternators....but on the Jetta, it wore the alt commutator down and wasn't worth it. On the starter, I was pressed for time and didn't have the time to order and wait for parts. On the starter, if you order one...make sure you get the right one for the transmission your car has (they're different).

So, if you have a parts store you buy most of your products from, consider going to them. If it fails, you can at LEAST try to get a warranty claim. Like I say, sometimes it pays to buy local.

OTOH.... you could buy new too. Maybe you wouldn't have that issue. IDK how Amazon in on warranty items after several yrs.

.

 

[Gruni14]

If you remove the alt, you should be able to peer inside or pull off the black plastic cover and see if the commutator is goofed up. If it's good, not heavily grooved, You could buy the parts and rebuild it yourself. They aren't that expensive or difficult to do. Pretty sure the diode kit and brushes are all in one, but it's been a while since I looked at a vw alternator. I'm sure you can buy the parts you need for it. And put a new Linton (quality) pulley on it.

There's probably a Y/T video on that. If the rest of your alt is new enough, might be worth doing.

 

[Mozambiquer]

Big fuses above battery are in tact. Pulley only spins in one direction, so it should be good. Exciter wire getting 12V with key set to ON. What's the other wire in that plug do? It's also getting 12V. I assumed it was ground, but I appear to be wrong.

I pulled the battery off the car and it took almost 24 hours to fully charge on my 2A charger. I'm getting 12.5V with car off, same with car on, but now I'm getting a touch more volts when I rev. Still not even 13, though. Getting nothing from alt stud to ground.

Should I consider replacing the regulator or the whole alternator. 5 years seems like trash to me. I won't be using Valeo again. Looks like I paid $260 for that in 2020 and it's now about $100 more.

How many miles have been in that 5 years?
Has there been any coolant, oil or fuel leaks on the alternator?
The Valeo are better than the new Bosch ones, since Bosch was bought out by a Chinese company SEG. And they do last very well, but any alternator will fail if they get oil, fuel or coolant on them, (fuel is common on an alh because of injection pump leaks.)
Also running with a bad battery will put a lot of extra strain on the alternator.
I sell a lot of the Valeo alternators, my price is $295 plus shipping still. www.anchormotorworks.com/shop

 

[Nuje]

This. They usually last one TB interval, rarely two. I do the idler pulley as well.

I usually give the idler pulley a spin and if it spins a little too freely, but still doesn't have any play, I just pop off the seal, squeeze in some bearing grease, put the seal back on....smooth like butter and good for another 100K.

 

[Justin Rizzo]

How many miles have been in that 5 years?
Has there been any coolant, oil or fuel leaks on the alternator?
The Valeo are better than the new Bosch ones, since Bosch was bought out by a Chinese company SEG. And they do last very well, but any alternator will fail if they get oil, fuel or coolant on them, (fuel is common on an alh because of injection pump leaks.)
Also running with a bad battery will put a lot of extra strain on the alternator.
I sell a lot of the Valeo alternators, my price is $295 plus shipping still. www.anchormotorworks.com/shop

40-50k max. Now that you mention it I did have very minor top seal injection pump leak for several months towards the end of 2024. In the winter it turned into a big-boy leak and I changed the seals. That was probably in Jan/Feb. I had to get a new battery at that time, but I figured it was just coincidence. It was going on almost 6 years with that Bosch battery. Replaced valve cover two years ago, so there's not big oil leaks there. No coolant leaks either.

Yeah you're not charging; the most-likely reason is the alternator or regulator is toofed if the pulley only goes one way -- and typically, when they're intermittent they start making a lot of noise too.

But DO check the large wire from the alternator to the battery for damage or crunchies; if it, or the grounding (or the large terminal for it on the big fuse block on top of the battery) are high-resistance it will not charge either.

I thought the pully was only supposed to spin one direction when you lock it up with a screwdriver, no? I probably didn't clarify that when I described the pulley operation. It only turns on direction when I "locked" with with a screwdriver. I'll check the big wires for resistance tonight, that's a good idea. I had my battery box out last winter trying to diagnose a glowplug check light (still not resolved despite new plugs, harness, and relay). The connections looked good, but we have a lot of mice on our property, so who knows (we live next to farm land).

It looks like I can get a 120a Bosch voltage regulator for $35 on ebay. Is that a direct fit onto the Valeo? Might be worth a shot before I pull the entire alternator? I've heard Autozone can verify if it's the regulator that is causing no charge, but I'm not sure if that is true. That would be a huge time saver. I'm light on time due to my work, which is why I typically just buy replacement parts as a solution. That said, these alternators are expensive.

NEW GENUINE Alternator Voltage Regulator 120A OEM Audi VW 038903803F | eBay

Vw Audi part number 038903803F. All our parts are (NEW OTHER) unless otherwise specified. They may have been in storage anywhere from 1-30 years. Rubber parts, gaskets, hardware may need to be replaced and may not be useable.

www.ebay.com

 

[Genesis]

It is only supposed to turn in one direction. If it turns in NO direction when the alternator shaft is locked its toofed, and if it turns in BOTH its toofed. However, it will often appear to pass but slip under load in which case it makes nasty noises when it slips which you can definitely hear (coincident with the battery light coming on.)

 

[P2B]

It looks like I can get a 120a Bosch voltage regulator for $35 on ebay. Is that a direct fit onto the Valeo?

No, but @Mozambiquer sells a rebuild kit for the Valeo.