Alternator Rebuild

autenje

Veteran Member
Joined
May 21, 2007
Location
Little Rock, AR
TDI
2001 Jetta
I have a 2001 Jetta TDI ALH, 170,000 miles.

When I first start the engine the battery light stays on until I get the car up to speed or if I rev the engine a few times and I am starting to hear a screeching noise.

I am assuming I need to replace the pulley and replace or rebuild the alternator? This has never been done on the car before.

If I do have the alternator rebuilt can any alternator shop do the job or is this something VW TDI specific?

Should I go ahead and replace the serpentine belt and pulley while I am at it?

Thanks
 

Dimitri16V

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Jan 30, 2005
Location
DE
TDI
01 Golf, 04 Golf
check the brushes by pulling the regulator out. do change the belt and check the pulley for clutched action
 

cfm56

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Apr 26, 2007
Location
97068
TDI
2014 Jetta TDI SportWagen
like dimitri mentioned, verify your pulley operates the way it is supposed to on your tdi (clutched action), then either replace the alternator or rebuild it. if it you have nothing to do with your time you can rebuild it and reuse your pulley if its good, if not just purchase another alternator and keep on truckin. If you do decide to purchase a alternator from autozone or your local auto part store, verify the pulley that comes on it is a clutched pulley.
 

85_305

Banned
Joined
Jun 20, 2010
Location
Buffalo NY/FT Bragg, NC
TDI
1999.5 Jetta 5spd
Sounds like the clutched pully is shot. I would veer away from rebuilding the alt; I've heard bad things about not buying a brand new Bosche or at least an oem rebuilt Bosche. A new alternator will come with a new pulley.
 

aja8888

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Dec 25, 2007
Location
Texas..RETIRED 12/31/17
TDI
Out of TDI's
Sounds like the clutched pully is shot. I would veer away from rebuilding the alt; I've heard bad things about not buying a brand new Bosche or at least an oem rebuilt Bosche. A new alternator will come with a new pulley.
Typically, the OEM rebuilts and aftermarket rebuilts come with the wrong pulley. At least that is what I have run into.
 

85_305

Banned
Joined
Jun 20, 2010
Location
Buffalo NY/FT Bragg, NC
TDI
1999.5 Jetta 5spd
Typically, the OEM rebuilts and aftermarket rebuilts come with the wrong pulley. At least that is what I have run into.
I've put 3 oem Bosche units on from Car Quest and haven't had any issues with an incorrect pulley? How do you know that the wrong pulley has been put on?
 

aja8888

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Dec 25, 2007
Location
Texas..RETIRED 12/31/17
TDI
Out of TDI's
I've put 3 oem Bosche units on from Car Quest and haven't had any issues with an incorrect pulley? How do you know that the wrong pulley has been put on?
TDI's have a clutching pulley that only spins in one direction whereas the gassers don't have that. The last alternator I bought had the gasser pulley on it. There are 100 threads here about the pulley. Maybe yours had the correct one.
 

85_305

Banned
Joined
Jun 20, 2010
Location
Buffalo NY/FT Bragg, NC
TDI
1999.5 Jetta 5spd
Yes I know TDI's have that silly clutched pulley; thats what went out on my last alternator so they just replaced the whole unit. I haven't heard of the gasser pulley being installed though. So I'm assuming you received the alternator, you messed with the pulley, and realized that it was bi-directional?
 

aja8888

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Dec 25, 2007
Location
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TDI
Out of TDI's
Yes I know TDI's have that silly clutched pulley; thats what went out on my last alternator so they just replaced the whole unit. I haven't heard of the gasser pulley being installed though. So I'm assuming you received the alternator, you messed with the pulley, and realized that it was bi-directional?
I checked the new pulley and it was clearly a gasser one. It also has a smaller outside diameter and a different size internal spline. The Metalnerd pulley removal tool has a spline on one end to remove gasser pulleys.
 

85_305

Banned
Joined
Jun 20, 2010
Location
Buffalo NY/FT Bragg, NC
TDI
1999.5 Jetta 5spd
Interesting. I guess that if my alternator were to ever go out again (knock on wood that it doesn't; what a pain in the butt), I'll have to make sure it's got the correct pulley. Thanks for that!
 

aja8888

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Joined
Dec 25, 2007
Location
Texas..RETIRED 12/31/17
TDI
Out of TDI's
Interesting. I guess that if my alternator were to ever go out again (knock on wood that it doesn't; what a pain in the butt), I'll have to make sure it's got the correct pulley. Thanks for that!
;);) There is a world of good stuff here! I am amazed at what I find from time to time.

Stay warm,

Tony
 

PDJetta

Top Post Dawg
Joined
Nov 6, 2003
Location
Northern Virginia
TDI
'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
Interesting. I guess that if my alternator were to ever go out again (knock on wood that it doesn't; what a pain in the butt), I'll have to make sure it's got the correct pulley. Thanks for that!
It would probably be wise whenever you replace your failed alternator pulley to save the old one. Then, if you ever need to replace your alternator, you can remove your good pulley and put the bad pulley on the now bad alternator (now a core) and turn it in when you get a remanufactured alternator. You now have your good pulley in case you need it.

--Nate
 

turbocharged798

Veteran Member
Joined
May 21, 2009
Location
Ellenville, NY
TDI
99.5 black ALH Jetta;09 Gasser Jetta
Is the pulley required for core exchange?

FIY, I just found that VW sells the voltage regulator/brush assembly for $50. The bearings you can replace with sealed standard bearings. You can pretty much rebuild your own alternator as the parts seem to be readily available.
 

85_305

Banned
Joined
Jun 20, 2010
Location
Buffalo NY/FT Bragg, NC
TDI
1999.5 Jetta 5spd
It would probably be wise whenever you replace your failed alternator pulley to save the old one. Then, if you ever need to replace your alternator, you can remove your good pulley and put the bad pulley on the now bad alternator (now a core) and turn it in when you get a remanufactured alternator. You now have your good pulley in case you need it.

--Nate
Sound advice! Though I'm not 100% sure my last alt was actually bad, I'm prettty sure the pulley was shot. My problem actually ended up being my excitor wire was broke. Boo on that. What an adventure.

Is the pulley required for core exchange?

FIY, I just found that VW sells the voltage regulator/brush assembly for $50. The bearings you can replace with sealed standard bearings. You can pretty much rebuild your own alternator as the parts seem to be readily available.
When *I* was looking to rebuild that alt, I couldn't find any parts at all for it. Nobody actually carried any rebuild parts.
 

ymz

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Joined
May 12, 2003
Location
Between Toronto & Montreal
TDI
2003 Jetta TDI Wagon, 2003 Jetta TDI Wagon
I just found that VW sells the voltage regulator/brush assembly for $50. The bearings you can replace with sealed standard bearings. You can pretty much rebuild your own alternator as the parts seem to be readily available.
Unless the rings on the rotor are worn... We still have the factory alternator at 398,544 miles, and I doubt that when it wants to give up the ghost we'll be able to rebuild it just by throwing a voltage regulator / brush assembly or bearings into it...

BTW: depending on which make of alternator you have (Hitachi alternators can't be rebuilt), you can probably find an aftermarket brush assembly for even less than $50...

Yuri
 
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ymz

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May 12, 2003
Location
Between Toronto & Montreal
TDI
2003 Jetta TDI Wagon, 2003 Jetta TDI Wagon
Yes... for Valeo alternators, the regulator's more expensive - and harder to get... Now that I looked into it, I see that the Bosch regulators have gone up a bit as well... last time I was thinking ahead, I could have gotten an aftermarket one for less than $50... perhaps I should have, but... as I said above, I don't think that when my alternator goes, a regulator will suffice...

Yuri
 

csstevej

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2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
For whats it's worth I have 225,000 miles on my alt . It is a non pulley type and came that way from South America when the car was built:eek:.
 

PDJetta

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Location
Northern Virginia
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'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
Sound advice! Though I'm not 100% sure my last alt was actually bad, I'm prettty sure the pulley was shot. My problem actually ended up being my excitor wire was broke. Boo on that. What an adventure.



When *I* was looking to rebuild that alt, I couldn't find any parts at all for it. Nobody actually carried any rebuild parts.
Yea, but I thought of keeping the old pulley after I threw it out!:(

As for replacing bearings as I understand it, all bearings have a universal part number on them and as long as you get a name brand with the same number, you are OK. The bearings press onto the shaft supposidly.

I may try to solder in new brushes into my voltage regulator if they ever wear out.

--Nate
 
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aja8888

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Dec 25, 2007
Location
Texas..RETIRED 12/31/17
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Out of TDI's
As for replacing bearings as I understand it, all bearings have a universal part number on them and as long as you get a name brand with the same number, you are OK. The bearings press onto the shaft supposidly.

--Nate
To me that is strange, as most bearings, bronze or ball/roller, usually are pressed into the housing bore...:confused:
 

turbocharged798

Veteran Member
Joined
May 21, 2009
Location
Ellenville, NY
TDI
99.5 black ALH Jetta;09 Gasser Jetta
I may try to solder in new brushes into my voltage regulator if they ever wear out.

--Nate
You can't. I tried, the voltage regulator is a sealed unit. Once the brushes wear out, the whole thing is junk.

To me that is strange, as most bearings, bronze or ball/roller, usually are pressed into the housing bore...:confused:
The front bearing is pressed into the housing and the rear bearing is pressed onto the shaft. The rear bearing is pretty tricky to get off, but it's doable with enough patience.
 

autenje

Veteran Member
Joined
May 21, 2007
Location
Little Rock, AR
TDI
2001 Jetta
I take it I have to remove the alternator to replace the pulley? Is there a how to somewhere on replacing the brushes, bearings on the alternator?

thanks
 

floyd r turbo

Active member
Joined
Nov 18, 2006
Location
cumming, ga
TDI
2003 Jetta TDI
I think my alt is out, per Advance Auto parts alt check, and looked at paperwork from previous owner who replaced it via Goodyear reman unit in 7/08 for $357 plus install and tensioner and install = total $856 large, ouch. It only lasted 35k miles. Currently pulling it myself to take to local rebuilder or maybe exchange.
 
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