Alternator Question

tdihopeful

Veteran Member
Joined
Oct 23, 2008
Location
California
TDI
03 2dr 5sp Golf
In an attempt to keep my car somewhat healthy as it is sitting waiting for me to install a new clutch, Helicoil in wheel bearing housing and general cleaning I decided to start and run the engine for a while. I noticed that the alternator wasn't spinning at idle. Is this normal? From what I understand the ecu makes changes to the output of the alternator based on electrical requirements from various systems on the car but it seemed to me that the alternator shouldn't be standing still. I don't really know however to be honest thus thanks for taking the time to help me understand this.
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
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
Sounds like your freewheeling clutch is toast.
it can be changed while on the car. You just need the metnerds tool kit to do it.
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Daughters car, 2005 Golf TDI Mine, all 5 spds
If your car is at idle do you mean that the alternator pulley is spinning but the fins inside the alternator housing are not turning? If so your alternator pulley is in need of replacement. Or are the fins turning so fast you can’t see them on either car?

The only reason you alternator shouldn’t be spinning at idle is because you have removed the serpentine belt. If you’ve not done that and the alternator is not spinning then you’re car is not charging.
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI
🤯🤯🤯
Not sure what to think... Yes, it should spin at idle, both on the TDI and on your Subaru. If it isn't, then there's a problem, and that would most likely be the clutch pulley on either of those.
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Asheville, NC
TDI
2002 jetta Wagon
The freewheeling pulley will always turn the alternator like pedaling a bike it will continue spinning once the engine slows down to prevent damage.
Check voltage present when running and not running. If it's higher when running the alternator is turning
 

tdihopeful

Veteran Member
Joined
Oct 23, 2008
Location
California
TDI
03 2dr 5sp Golf
Prairieview why do I ask for assistance? There is a saying-The only stupid question is the question that isn't asked. I don't want to be stupid? Ignorant? The more information I have to work with the better my chances are of gleaning useful information essentially however in spirit. I assumed that the information I was provided was accurate and then thought just out of curiosity I would compare my Jetta alternator to my Subaru alternator. Found that they seem to function the same. Both cars seem to have no battery charging trouble thus? Was there or is there something wrong with my methodology that you would like to bring to my attention?
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI
Prairieview why do I ask for assistance? There is a saying-The only stupid question is the question that isn't asked. I don't want to be stupid? Ignorant? The more information I have to work with the better my chances are of gleaning useful information essentially however in spirit. I assumed that the information I was provided was accurate and then thought just out of curiosity I would compare my Jetta alternator to my Subaru alternator. Found that they seem to function the same. Both cars seem to have no battery charging trouble thus? Was there or is there something wrong with my methodology that you would like to bring to my attention?
It comes down to that if they aren't turning at idle, there's a big problem that needs to be addressed.
 
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