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Discussion Starter · #1 ·
Basically I just bought my first dub, a 2001 jetta tdi. Everything seemed fine, I drive it off to school... I get off school, and the battery is dead. I kinda looked for the obvious and see if I left anything requiring power on NOTHING, I call my dad, get it boosted.. she starts right up. I drive it, and i notice the lights are very dim... the abs light is going on and off.. just really crazy ****. I stop it, it wont start again... yet again get it boosted, this time it took longer to "charge up" and the abs lights went away. I kinda was intially figuring out that the alternator isnt putting out enough juice. I whip out the multimeter everything seems legit putting out a nice steady amount. Whats interesting tho, I put on a alternator tester and if I rev the car to ike 3k rpms once I start it , and all of a sudden the alternator kicks in. If I don't rev it up, it doesnt kick in.. hence it not charging the battery, Id like to know if this is normal, is it a sign that ill be needing a new alternator soon? Maybe seems kinda like a n00b question but really I drove lots of other cars and only this seems to be actin up. I wish I had a vagcom to see if its sending any errors, sadly im bit dried up from just getting the thing few days ago. So any help greatly appreciated..
+ For some weird reason, with everything turnd off in the car.. when I put a new battery in, it sparked at the connectors ( closed a circuit), possibly a short? ideas?
 

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Re: Weird battery charging issue (Cozmanator)

What did your multimeter read?
Car "on" but not running: you should read 12ish volts, with a charged battery
Car "on" and "running": voltage should jump to 13.5-14.5V. If it doesn't you have alternator problems.
The battery cable will always "spark" a little bit when you connect them as the alarm, clocks, etc draw a bit of current even with everything else off.
 

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Discussion Starter · #3 ·
Re: Weird battery charging issue (Vincent Waldon)

It was well within those ranges. The thing I dont get is why I have to rev it up to 3000 rpms once I start the car for the alternator to kick in.

+ thx for the battery question, I thought something was wrong haha,
 

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The thing I dont get is why I have to rev it up to 3000 rpms once I start the car for the alternator to kick in.
Sounds like the voltage regulator is getting flakey. You could have a mechanic do a load test on the electrical system.
How's the serp belt look? Is there adequate tension on it? How old is the battery?
How to the terminals look? If they're dirty, disconnect them and clean them until they shine. Also, inspect and clean the ground under the battery tray.
 

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Discussion Starter · #6 ·
Re: (OttoSchultz)

I just bought a new battery today, so the terminals are all clean. Ill definitely check out the serpentine belt! Ironically I bought it off a mechanic, I asked him bout it.. he told me its normal, which is kinda hard to believe. Its like I hop in, i start it.. If i just let it be, itll run out of power and drain the battery out , if I hop in.. rev it up and let the alternator kick in.. it keeps it charged up nicely. Its werid what co-relation me revving the engine and the alternator kicking in
thx again for the reply!
 

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Discussion Starter · #7 ·
Re: Weird battery charging issue (jd2355)

Quote, originally posted by jd2355 »
hey just peekn in,is there a differance between gas altenators and the ones on the diesels on vw or are they the same?

Im pretty sure there all the same, just the TDi ones have higher amp output. Might be wrong.
 

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Re: Weird battery charging issue (Cozmanator)

Quote, originally posted by Cozmanator »
The thing I dont get is why I have to rev it up to 3000 rpms once I start the car for the alternator to kick in.


Does the red BAT LED in the cluster come on when you turn the key to "on"? Sounds like the alternator is not getting the excitation voltage.
If not, there's a wiring issue from the cluster to the alternator or a problem with the cluster itself.
If it is then your alternator has an issue... either internally (most likely voltage regulator) or externally...sometimes wiring at the back. It should begin charging at idle.
 

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Re: Weird battery charging issue (Cozmanator)

Quote, originally posted by Cozmanator »

Im pretty sure there all the same, just the TDi ones have higher amp output. Might be wrong.

the drive pully size the same to, was just kind of wondering if somebody put a gas engine altenator or differant pully on, my 92 golf gas engine does the same thing in the winter time but I just give it a light throttle tap after start up and live with it but 3k rpm is a little much.
 

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Discussion Starter · #10 ·
Re: Weird battery charging issue (Vincent Waldon)

Quote, originally posted by Vincent Waldon »

Does the red BAT LED in the cluster come on when you turn the key to "on"? Sounds like the alternator is not getting the excitation voltage.
If not, there's a wiring issue from the cluster to the alternator or a problem with the cluster itself.
If it is then your alternator has an issue... either internally (most likely voltage regulator) or externally...sometimes wiring at the back. It should begin charging at idle.

Hmmm... Now I know at least that its not normal! Im gunna look into getting a new alternator, hopefully rebuilt ( OEM/Bosch) new is a little out of my range for now. The way it looks positioned, it looks like a real PITA to remove. Once the alternator gets going, it sends off plenty of power.. so the " voltage regulator" prolly went bad? Thanks again man!
 

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If not, there's a wiring issue from the cluster to the alternator or a problem with the cluster itself.

Is there actually wiring between the alt and the cluster? I thought everything went to the ECU first, and then to the cluster.
 

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Re: Weird battery charging issue (Cozmanator)

How many miles are on your car, and if you know, how many are on the alternator?
It could be a dead voltage regulator or a clutch pulley going out/being dead.
VW's have a clutched alternator pulley to extend the life of the alternator as well as increase fuel mileage. If it seizes (very common) the alternator is creating juice ALL the time, which can cause the unit to get hot and then you get excess wear on regulators, brushes, and possibly bearings.
I took the alternator off my car and had it rebuilt while I waited (not even an hour) for $170. That's new bearings, new brushes, regulator, and a clutch pulley. It tested over 130 amps before the alternator guy's test motor couldn't turn it anymore. He said he sees a lot of the Bosch clutched alternators and the alternators themselves are good for over 200K, but the clutch pulleys start to give around 75K miles.
Either way, if your car is an '01 I'd say just nut up and get the alternator rebuilt. It'll likely solve your issue and it will save you from a lot of headaches. Just have fun getting it out on your TDI. It was a pain in the ass for me!!
 

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Re: Weird battery charging issue (DZCad90)

Quote, originally posted by DZCad90 »

...or a clutch pulley going out/being dead.

That's a great catch... particularly given the "doesn't work till it's revved up to 3000 rpm" clue.
Unfortunately for the OP a couple of special tools are required to replace the pulley...if that does in fact end up being the problem... wwww.metalnerd.com, among others carry the tools.
The test is to remove the serp belt and then spin the alternator pulley by hand... it should latch in the forward direction and then release when spun backwards.
 

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Quote »
If it seizes (very common) the alternator is creating juice ALL the time, which can cause the unit to get hot and then you get excess wear on regulators, brushes, and possibly bearings.

I thought it was the other way around....if the alternator seizes, the clutched-pulley freewheels so you can keep driving without shredding the serp belt.
 

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Re: (OttoSchultz)

I think if the alternator seizes the pulley would freewheel briefly.. but my guess is that it would soon grenade as it's not intended for those rpms or duration.
It's real purpose is to decouple the momentum of the spinning alternator armature from the serpentine drive belt system and specifically the crank sprocket. Due to the choppy nature of how power is supplied to the crank sprocket and the mechanical advantage the small-diameter alternator pulley has on the larger-diameter harmonic dampener pulley the alternator's momentum causes the drive belt to load and unload... placing stress on components driven by the belt... in particular the crank sprocket itself.
Somewhere on Youtube you can find the odd video of someone with a seized alt pulley... the serp belt (and tensioner) vibrate like crazy.
This first revealed itself with the early version of the serp drive belt system on the AAZ... an engine already blessed with a weak crank sprocket. VW's response was to add the clutched alternator pulley and the design stuck thru subsequent version of the serp drive belt.
Based on what I've read I'd say the alt pulley generally fails "open" rather than "seized"... in fact often "open" enough that it flies off. http://www.tdiclub.com has several threads of folks reporting the pulley flying out of the engine compartment.
 

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Discussion Starter · #16 ·
Thanks for the suggestions everyone!
Im deff gunna get that Alternator changed, it just looks like Im better off getting somone to take it out.. by the looks of the way its positioned I think I have to take some other stuff from underneath. Being I dont have a garage for now. If i wait out till spring/summer I can probably do it myself. Does anyone recommend the most cost effective way? Vincent I see your also from Alberta, any tips that maybe can be done locally?
 

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Re: (Cozmanator)

Quote, originally posted by Cozmanator »
Thanks for the suggestions everyone!
Im deff gunna get that Alternator changed, it just looks like Im better off getting somone to take it out.. by the looks of the way its positioned I think I have to take some other stuff from underneath. Being I dont have a garage for now. If i wait out till spring/summer I can probably do it myself. Does anyone recommend the most cost effective way? Vincent I see your also from Alberta, any tips that maybe can be done locally?


Though I said it was a pain, it took me about 2 hours.
You have to remove the belly pan, serpentine belt, belt tensioner, AC Compressor (Remove bolts, leave connected, hang with wire ties / wire on the side) and the right hand radiator fan to remove from the bottom.
Some folks say they have done it from the top but again that looked like a pain in the ass too. Pick your poison.
 

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Re: (Cozmanator)

Quote, originally posted by Cozmanator »
Vincent I see your also from Alberta, any tips that maybe can be done locally?

Don't know anyone in Calgary... sorry.
 
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