TDI Alternator Gas Alternator Swappable?

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
You will probably have to exchange the pulleys, but yes they are interchangeable if they are the same power rating. My guess is the gas car will only have a 90 amp, though.

-Jason
 

BleachedBora

Vendor , w/Business number
Joined
Oct 16, 2003
Location
Gresham, Oregon
TDI
'81 DMC-12, '12 Audi TT 418 hp/383 tq, '08 GL320 CDI 275 hp/448 wtq - '81 Caddy ALH, '04 Golf BEW 2" Lift, '85 HMMWV
Actually the pulleys are both 6-rib systems. Most of the '99s regardless of 2.0, 1.9, 1.8T or VR6 should all have 120 amp systems. If you have a 90 amp it's a rarity.
-BB
 

jasonTDI

TDI GURU Vendor , w/Business number
Joined
Apr 26, 2001
Location
Oregon, WI
TDI
12' RAM 2500 QC,LB. 2019 Cherokee 2.0T
BleachedBora said:
Actually the pulleys are both 6-rib systems. Most of the '99s regardless of 2.0, 1.9, 1.8T or VR6 should all have 120 amp systems. If you have a 90 amp it's a rarity.
-BB
Wrong.

Autos were all 90 the manuals were 120.

Swap the pulley or better yet get a new one. The key is it has to have a sprague clutch in it.
 

jasonTDI

TDI GURU Vendor , w/Business number
Joined
Apr 26, 2001
Location
Oregon, WI
TDI
12' RAM 2500 QC,LB. 2019 Cherokee 2.0T
dogdots said:
I doubt that the pulley on the gasser is a one way clutched pulley, but I could be wrong.

Solid one on the gassers.
 

BleachedBora

Vendor , w/Business number
Joined
Oct 16, 2003
Location
Gresham, Oregon
TDI
'81 DMC-12, '12 Audi TT 418 hp/383 tq, '08 GL320 CDI 275 hp/448 wtq - '81 Caddy ALH, '04 Golf BEW 2" Lift, '85 HMMWV
You're right, momentary insanity :)
Still, I stand by they should all be 120a systems!
 

alphaseinor

TDI Innovator Vendor , w/Business number
Joined
Jul 30, 2006
Location
Denton, TX
TDI
'03 Jetta TDI 780,000 miles (totaled out), 01 Audi TT 225 Quattro 230,000 Miles (runs great!), 00 Cabreetle Beetle dash, ALH & MK4 harness Swap
I've installed many 120A alternators in 90A cars... IIRC they all should be the same
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
To make the crankshaft pulley's life easier, and to make the alternators life easer. Go watch a gasser or early TDI... rev it up and let it return to idle, you can see the stress on the belt go the other direction for a moment.

-Jason
 

festivenuts

Veteran Member
Joined
Apr 5, 2005
Location
Long Island, NY, USA
TDI
Golf; 1999 a4; Black; 158,000 miles
Ugh starting to get a headache with this alternator.

Any suggestions? I'm not sure if I'm clever enough to change the alternator.

Could it possibly be a malfunctioned alternator regulator. I just find it odd that I come back after 2 months and alternator just doesn't work...

I don't know where to go from here any suggestions :(
 

festivenuts

Veteran Member
Joined
Apr 5, 2005
Location
Long Island, NY, USA
TDI
Golf; 1999 a4; Black; 158,000 miles
yea my tdi has low idle and shakes as well (i push the pedal a bit to keep it smooth)

just picked up a 2003 120amp alternator from a bug. time to follow wingnuts guide

wish me luck!
 

Steel

Veteran Member
Joined
May 11, 2005
Location
Tucson, Arizona
TDI
95 isuzu pickup longbed. "Tiny Ox"
Thanks JB. So basically, the rate of acceleration (and deceleration) of the crank at idle is a lot more severe than a gasoline engine hence the one way clutch? One would think that they'd one way clutch everything that isn't indexed to the crankshaft then... or use a heavier flywheel. Hmm.
 

jetta 97

Vendor
Joined
Dec 25, 2008
Location
Dallas (McKinney) ,TX ,USA
TDI
2 X Jatta MK5 2006
90amp. alternator was update to 120amp. So if you have 90amp on your car you should update to 120amp.
Gas engine 120 has same alternator and pulley. 90 is not because it has solid pulley, but 120 has same .
 

festivenuts

Veteran Member
Joined
Apr 5, 2005
Location
Long Island, NY, USA
TDI
Golf; 1999 a4; Black; 158,000 miles
thanks to everyone for helping me out and steering me the right direction

thanks to wingnuts excellent write up i swapped out the broken alternator for a functioning 2003 vw bug 120 alternator

all is well now :)
 

intro

Veteran Member
Joined
Dec 10, 2007
Location
MA
TDI
02 Jetta Wagon
Final word was that a 120 amp alternator will work on a TDI or a gasser? They are swappable either way? I see one at IDParts I'm interested in for my 2.0L AZG.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
Yes. Correct. However, rebuilding them is the best option. They are not difficult to rebuild with new brushes and regulator. If the stator where the brushes ride is severe worn though, more than a mm or so, then it also needs to be replaced and that's where a junkyard one is best to rebuild. There is a thread here somewhere about how to rebuild them and links to all the OEM Bosch parts.
 

intro

Veteran Member
Joined
Dec 10, 2007
Location
MA
TDI
02 Jetta Wagon
Yes. Correct. However, rebuilding them is the best option. They are not difficult to rebuild with new brushes and regulator. If the stator where the brushes ride is severe worn though, more than a mm or so, then it also needs to be replaced and that's where a junkyard one is best to rebuild. There is a thread here somewhere about how to rebuild them and links to all the OEM Bosch parts.
Thanks, I was hoping to rebuild but the pulley turns to the left just fine when I insert a screwdriver and locks to the right, the voltage regulator looks within spec:



Not sure what else there is to rebuild or how deep I can get into things. The only thing I can think of is when I was tapping it into place I knocked something loose inside.

The service alternator light hasn't been showing in the dash, but it is there when I turn the key.

It did fail the bench test at Advance:





My thought was to order the TYC for cheaper. This Bosch didn't prove to do too well at 3 years.
 
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Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
Rebuilds are garbage. Do it yourself with proper parts, will be about $40 in parts, common tools do the job, you need to solder but it's not that bad
 
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