MKIV Golf alternator clutch pulley issue?

My 2004 Golf TDI (BEW) engine code recently began making sounds at idle, especially when AC is turned on or when stopped and turning the steering wheel. There is also a slight whistle sound sound at around 2,000 rpm while driving but that may be unrelated. I suspect the Alternator Clutch Pulley. I noticed the belt tensioner moving erratically the other day. I took a video which can be viewed at this link:
http://youtu.be/mbsmoEP3eT4
Also, I took the belt off and test the Alternator Clutch by locking the alternator with a screw driver and then seeing if the alternator pulley turned freely Counter Clockwise and locked clockwise. It is seized both ways, does not spin freely either direction.
This video I found at 2min 12 seconds discusses what my alternator pulley is doing which is seized when locked does not spin freely counter clockwise.
http://www.youtube.com/watch?v=fyosuYbPxr4
So does that mean I need to replace my Alternator clutch pulley. I have read up about a Metalnerd tool that makes it easier to remove or I plan to see if this tool can be borrowed from parts store.

Is it true that the alternator pulley on all A4-and-later TDIs are supposed to be a one-way (so-called "clutched") unit that turns the alternator when turned clockwise, and lets the alternator "slip" ahead when turned counter-clockwise? Since mine is seized and is locked when turning in both directions, that causes the belt tensioner to bounce around like crazy.

Is this a definite Alternator pulley replacement and a possible belt tensioner replacement?

Any advice would be appreciated.

Ken Bradford
2004 Golf TDI (BEW)
Plattsmouth, NE

Yup, yup, and yup...you've done a good job of tracking it down... everything you've posted points to the need to replace your alternator pulley.

Thanks. I will begin the quest to assemble tools and parts. Should I suspect the tensioner will need replacing or just wait until the alternator pulley is replaced.

Belt still looks great, Just replace summer 12 months ago.

Ken

The tensioner may need replacing too. A failed pulley stresses it. Especially replace the tensioner if its wheel is beat up.

"There is also a slight whistle sound sound at around 2,000 rpm while driving but that may be unrelated. "

I have that on my '04 (actually in the RPM range of 1400 - 2200 rpms) and I have narrowed it down to the timing belt, or roller, or tensioner, making noise. In my case, I don't think its a big deal. Been doing it for years and it is louder when the engine is cold and gets quiter once the engine warms up.

--Nate

Good advice on the belt tensioner, thanks.

Related to the whistle sound, I had thought it could be a leaking EGR pipe but did not want to take everything apart. I found this link which seem to be like mine.

http://forums.tdiclub.com/showthread.php?t=338948&highlight=MKIV+TURBO+NOISE

I am committed to not fix what is not totally broke or that I cannot with absolute certainty say is the problem. The whistle sound hits around 2,000 rpm, I can kinda isolate it when parted and my wife revs the motor to the back side of the engine.

My philosophy is to wait till it gets louder and I can feel with my hand the leak or see it.

Alternator pulley will be done and tensioner no question about that. Whistle sound will have to wait for more symptoms. I will inspect the belt and see if I can tell if the roller looks worn etc.

Ken

Problem solved alternator pulley replaced

I was able to replace the alternator pulley and it fixed the sound problem and the erratic movement of the belt tensioner movement.

Here is the before and after youtube video.

http://youtu.be/U4sbSVrJzMM

Thanks for everyone's input!

Ken
Plattsmouth, NE
2004 Golf TDI (BEW)

Am I correct in the assumption that the pulley is supposed (designed to) to spin counter clockwise and NOT clockwise when the fan is locked as show in the video?

My TDI developed an issue where the belt would sporadically squeal during normal driving conditions. Whenever the belt squeals the battery light comes on , and the headlights either dimm or get brighter. Drove car for a week like this.

I changed the alternator 2-26-2011, so my first guess was the belt tensioner or the belt (tho I replaced that belt on said date as well)...I noted that the shock on the tensioner was missing its boot so I replaced that shock, and the belt.

I tested battery for voltage and it was varying between 12.5 and 14.5 when the car was running at idle. Problem persists.

Today I drive car for 5 minutes, when I turn the A/C on the battery light comes on, I turn it off, battery light turns off. Limited belt squealing persists.

By the end of my drive all the gauges in my car locked in place, all the lights on the dash came on, and I made it to a parking lot and turned off the car. I checked to make sure belt was still in place as well as all pulleys. Looks good. Battery is drained and will not start.

Next guess is AUTOZONE alternator went bad after only 18 months. Well my pulley spins freely counter clockwise (with some resistance) and does NOT spin clockwise. I brought the alternator to autozone and they test it and say its Good.

Any ideas on this?

Is there tension on the belt? Did you have to relieve the tension to get the belt off?

Serpentine belts either work or they don't but a squealing belt strongly implies something is locked up. Is your AC working?

A/c works great. Power steering has been whining a little. I'm still convinced it's the alternator. There was a lot of tensioner, I did replace the tensioner shock and the problem was unresolved.

Well if you have no charge then the alternator is obviously not working

Will be installing a new alternator today. Guess I'll find out if thats really the problem...To make things worse I broke the Bosch alternator I picked up on friday attempting to install it. Snapped one of the ears off as I was attempting to mount it.

Just couple comments - I am far from an expert, but have been dealing with this alternator clutch pulley & serpentine belt tensioner issue for a couple years (on a 2004 Jetta TDI PD BEW).

I first had the standard squeaky serpentine belt, starting about 2 years ago. Took it to a shop, they said it was the tensioner. I ordered a new tensioner, and installed myself. Squeak didn't go away (stupidly, I didn't put on a new belt at the same time). No improvement whatsoever. Clearly, the shop was wrong, the tensioner was not the issue.

I then turned to google, and happily found tdiclub forums. After a bit of reading, I came to understand the likely culprit - a seized alternator clutch pulley. I checked it - yep, it was seized.

To be clear: With belt off, and a screwdriver keeping the alternator from spinning, the pulley should spin freely counter-clockswise, but seize clockwise. If it seizes in both directions, the "clutch" mechanism isn't working. I know of no way to fix it (would be nice if you could just grease it or something....).

So, I ordered a new clutch pulley. Being very low on cash, and figuring even a knock off would hold up for a few years, I bought one on Ebay. BIG MISTAKE!

It did work as it was supposed to for awhile. Not sure how long, but, eventually, squeaking came back. I checked the pulley again - bad. Seized. Go figure, a Chinese part didn't hold up for 5+ years, the way a German one would? Huh. Shocking.

PAY THE EXTRA MONEY AND GET A GATES OR INA PART.

As it turns out, the INA is now made in China - but, under the supervision, specification, and quality control of INA - so they should be fine. Its the knock-off manufactures who kick out bad parts. (The Chinese aren't incapable of producing quality parts - they just have to be forced to do it by foreigners).

A couple more comments:

To get the clutch pulley off, you need a special tool - I ordered a Metalnerd part. I think there's another tool available now - IDparts and worldimpex have one or the other.

Diagnosis: The squeaking from a bad clutch pulley is most evident at low RPM's (idle). You won't necessarily hear squeaking right away the moment the clutch pulley first goes bad (seizes). It works like this:

1) The clutch pulley seizes (for unknown reasons), causing:

2) The tensioner to swing wildly at low RPM's, causing:

3) The serpentine belt to wear down. Until the belt is worn down enough, you won't hear the squeaking (but will be able to see the tensioner swinging wildly).

If the clutch pulley is seized, and you just put on a new serpentine belt - the squeaking will go away. For awhile. Until the new belt is worn down. The tensioner, however, will swing wildly at idle from day one. Basically - gotta replace the pulley.

From another thread/post, there is a very convincing explanation as to why the issue kicks in at low rpm's, but is fine at higher rpm's:

First, one has to understand the reason for the clutch pulley:

Combustion engines (diesels in particular, apparently) create pulsating energy - when a cyclinder fires, there's a pulse of energy (in the form of rotation). There is a gap between pulses (the time between the firing of cylinders - a fraction of a second).

In the meantime, the alternator is spinning at very high rpms, with little friction - thus, the alternator has a lot of momentum. This, versus the engine, which is rotating at lower rpms, with a lot of friction. (cut power to an engine, and it will stop rotating almost instantly - cut power to an alternator, and it will keep spinning for a bit....so long as the clutch pulley is working correctly....).

Basically - in the gap of time where there is low rotational energy from the engine, there is a force trying to slow down the alternator - versus the alternator's high momentum, which is trying to keep speed up the engine). The two opposing forces - the engine's rapid reduction in momentum, versus the alternator's momentum - causes the stress on the serpentine belt & tensioner, causing the tensioner to pulsate wildly.

OK - so now that that is all clear - the reason this effect is most evident at low rpms (idle) - the lower the rpm, the greater the gap in time between engine firing - resulting in an extended period of time when the engine's lower momentum is trying to slow down the alternator, and the alternator's momentum is trying to speed up the engine (you can guess which of those two wins the battle....).

Conversely, at higher rpms, the gap in time between engine firings is low enough so as to not cause significant tension.

Enter the clutch pulley - the clutch allows for the alternator to keep spinning at a steady speed, unaffected by the engine's pulsating power. The slowing engine doesn't act as a drag on the alternator, and the high-momentum alternator doesn't try to speed up the engine.

Final comment: Although a bad pulley most often just results in the nuisance of having to change serpentine belts often, and perhaps eventual fouling of the tensioner, I have seen mention of much bigger problems as a result. Eventually, a bad alternator, and, so I've read, expensive "engine troubles" (I forget what, exactly).

Thanks for a great summary pentmeister!
A follow up comment and question. I had the symptoms of a seized alternator pulley (squeaking a lot, then not squeaking, etc. etc.) for the past couple weeks + but unfortunately did not identify the problem (or find this thread) until after my alternator pulley 'disconnected' itself from the alternator shaft. The damage to the pulley is significant, the ALT shaft looked pretty bad too. Fortunately I noticed the loss of power steering immediately, pulled over and removed the serp. belt before anything serious occurred (TB damage).
For those of you who have had a close look at the pulley and shaft, any chance I can just replace the pulley? Obviously I need to get it off and take a good look, but I though it was interesting that the 3 local places I called for parts said they dont offer a new pulley.

If you can get it off and the shaft on the alternator isn't buggered, yes.

Local part shops aren't liable to have the pulley. Non-TDI specialist repair shops will tell you that you that you have to install a whole new alternator. So long as the alternator shaft isn't totally buggered, that's hogwash. I would actually avoid a whole new alternator, as the after-market ones aren't as good as the OEM's. And the OEM's are a fortune to replace.

I would look towards Worldimpex, IDparts, or a few other online suppiers.

BTW the BEW alternator is easy to R&R, and contrary to popular belief you CAN R&R the ALH one without disassembling the entire front clip; I have successfully done so.

IDparts had the pulley when mine died and got one to me while on vacation 1,300 miles from home in a day. You gotta love parts suppliers who get it done when you need it; the alternative was a stealer and a HUGE bill.

I've been searching around and can't find my specific problem related to charging and belt noise - hopefully the experts here can suggest a diagnosis.

The charge light came on in my 2005 Golf BEW (~95K mi) on the way to work yesterday. Intermittent by the time I got home (~30 miles and 3 start/stops later), and when I checked the voltage before turning off it was reading 14.2V. I read this thread, decided it was the pulley based on the fact that the light sometimes went off after revving (not while revving). I got a chance to test again tonight and there was a louder intermittent bearing squeal from the belt area and the tensioner is bouncing a little. The voltage was now only 12.1V while running and just under 12.0 with load (lights, AC, etc). My guess was now that the pulley was definitely the culprit.

Here's the kicker though - when I took off the belt and tested the pulley, it locked clockwise and turned smoothly and firmly counterclockwise.

I'm wondering now if it's the alternator bearings making the noise due to the lower voltage, but would the tensioner be bouncing if the pulley is working? I tried to use the 'broomstick trick' to 'feel the noise' of the bearings in the alternator (where you touch a wooden pole to the suspected component and press behind your ear to transmit the sound through a solid), but didn't really sound that bad.

Any suggestions much appreciated!

If your alternator bearings are binding, your tensioner may. Bounce too.wi
erta

Could just be the belt. The belt is cheap, and you'd likely want to replace it if/when replacing the pulley and/or tensioners.

So - try a new belt, and see what happens.

If no change, then it is possible the tensioner itself is bad, while the pulley is still good.

I always thought the tensioner would always bounce a little bit. Not so. I replaced the tensioner & belt recently - no bounce at all, perfectly smooth.

If after changing belt & tensioner, still no better, then its time to suspect the alternator & alt pulley again.

Personally, I'd give changing the alt pulley try. If no better, then its onto the alternator itself....here I am no expert - could it just be the regulator/brushes? (I once suspected this, and bought the part, though never replaced it, as the alt pulley was the issue).

It would be nice to be certain of what the problem is, and avoid replacing parts that aren't bad - but I don't know of a fool-proof diagnosis methodology.

puntmeister said:

It would be nice to be certain of what the problem is, and avoid replacing parts that aren't bad - but I don't know of a fool-proof diagnosis methodology.

Click to expand...

Well, that makes feel better about the extra parts I bought. I have a new pulley on the way in the mail from before I tested it last night, and now have a new (reman) alternator today to install this weekend. I almost bought a tensioner with the alternator, and sounds like that could be in my future, too! The belt's <10k miles old as I did the TB around 88k.

Thanks for the tips- I'll put the alternator on tomorrow after I raid my kids candy and have a good sugar buzz going.

puntmeister said:

From another thread/post, there is a very convincing explanation as to why the issue kicks in at low rpm's, but is fine at higher rpm's:

First, one has to understand the reason for the clutch pulley:

Combustion engines (diesels in particular, apparently) create pulsating energy - when a cyclinder fires, there's a pulse of energy (in the form of rotation). There is a gap between pulses (the time between the firing of cylinders - a fraction of a second).

In the meantime, the alternator is spinning at very high rpms, with little friction - thus, the alternator has a lot of momentum. This, versus the engine, which is rotating at lower rpms, with a lot of friction. (cut power to an engine, and it will stop rotating almost instantly - cut power to an alternator, and it will keep spinning for a bit....so long as the clutch pulley is working correctly....).

Basically - in the gap of time where there is low rotational energy from the engine, there is a force trying to slow down the alternator - versus the alternator's high momentum, which is trying to keep speed up the engine). The two opposing forces - the engine's rapid reduction in momentum, versus the alternator's momentum - causes the stress on the serpentine belt & tensioner, causing the tensioner to pulsate wildly.

Click to expand...

FINALLY an explanation as to how a bad clutched alternator pulley relates to the SB tensioner!!! Thank you Puntmeister! Been asking youtube video posters showing how the SB tensioner bounces a lot when there is a bad clutched pulley but they DON'T EXPLAIN WHY!!! I think I can safely say that my squealing noise might just be that. I already replaced the belt AND the tensioner with no improvement. Haven't done the pulley rotating test (without the belt on) yet though.