Bouncing belt tensioner

I noticed a new ticking noise the other day in my 04 TDI Jetta PD. Popped the hood and found that the serpentine belt tensioner was bouncing. After some searching here is sounds like it could be the alternator pulley being siezed. Does that sound reasonable? I'm not sure if/when the tensioner was replaced. I'll have to look through the records from the PO. If I replace the Alt. pulley, should I also be looking at replacing the tensioner?

Also is there a good online place for looking up parts and part numbers for VWs?

Yes, it's your alternator pulley. Change it. I would replace the tensioner while you are in there along with the belt. The bouncing really kills tensioner.

www.idparts.com has all the parts you need.

Cool, thanks! Do I need a tri-sqaure bit to get the alternator pulley off? If so which one?

You will need the metalnerd alternator pulley tool. Idparts has that too.

I can rent you the tools if you need. You don't need to replace the tensioner on the PD engines. Not the same as on the ALH engines. But you do need that pulley.

You don't need to replace the tensioner on the PD engines.

Click to expand...

When it does a lot of bouncing from a failed alternator pulley, the spring gets pretty weak. I have experienced this first hand.

I tried the screwdriver to stop the fins trick to test the pulley last night. I couldn't turn the alternator pulley either direction by hand. Kaput, yes? I've got a tensioner, belt, and alt. pulley coming today. And a friend is lending me the tool. Is there a puller needed to get the pulley off? Or might there be a DIY about replacing the tensioner and pulley?

this is for the pulley

http://forums.tdiclub.com/showthread.php?t=234251

The pulley is bad. No puller needed. The pulley will be TIGHT!!!!!! Counterclockwise to loosen, like any ordinary nut/bolt.

--Nate

There have been people that have broken their wrench getting it loose FYI. That is how tight it is. Where gloves and make sure if the wrench does break you won't get injured.

Thanks for all the tips. I've got everything I need to tackle it this weekend. Hopefully all goes well. Maybe I'll squirt on penetrating oil on the alt pulley thread tonight and let it sit over night.

I found that rubber gets down in the grooves of the crank pulley and cause bounce. Try cleaning it.

I pulled the alt pulley tonight. Wasn't all that tight. It was tight, but not break your wrench tight. Got the new on one before it got dark. Tomorrow the tensioner and a new belt.

concours I'll check the grooves on the crank pulley, thanks.

Success. All went well. And now no more bouncy tensioner.

Thanks for this thread, I went out and checked mine after reading this, bouncing like crazy and the pulley is locked up, just ordered the pulley, tool and tensioner.

Pulley and tensioner replaced tonight. No more bounce!

Pulled alternator today and took back to place I bought it Tri-State in newark,DE. Explained to them that this alternator purchased there 2 years ago with a solid pulley has caused me to eat through 3 tensioners until I read about this here. They kept the alternator and ordered the clutch pulley for installation in the morning. No charge. Good guys. Getting alternator out was a PIA! I don't remember it being this difficult when I did it 2 years ago. I think I took out intercooler pipe and out though the bottom. This time I went through top and had to pull hoses and wires etc.

Anyway after doing the heater core yesterday, this was just icing on the cake.Hopefully this junkpile will run for more than a week. Then this summer it is timing belt time...

Note. The 99.5 has a split hvac case. Heater box is seperate.No evap removal. Youtube video was helpful.

I think I'll order the metalnerd tools for this next time the damper bounces.

Thanks guys.

r72gsaol said:

Pulley and tensioner replaced tonight. No more bounce!

Click to expand...

Yeah. Glad this helped someone else out.

I had the same prob on my 04 Jetta wagon a few months ago. Took the belt off, tested the alt pulley, it turned fine (seemingly, although I have no idea what resistance to turning a new one might present). I changed my tensioner & noticed that the new one's spring was much stronger than the old one. The bad news is that after about 3 weeks the rattliness was back. It goes away above idle, but it rattles pretty loudly at idle. Do you experienced dudes think I may have alternator pulley issues that just weren't obvious? I'll take a look at the grooves of the crank pulley, but I'd be interested to hear from BenZoil if your fix works long-term for you.

Yes, replace your alternator pulley if the tensioner is bouncing.

Yes X 2.

--Nate

Yes, replace the alt pulley. One way to test it, when you have the belt off. Give the alt pulley a quick spin by hand in the direction the engine spins. But hang onto the pulley. It should spin for a second after you stop spinning it. If it doesn't it's seized. and time for a new one.

My tensioner is rocking back and forth at regular intervals (2 seconds or so) like a rocking chair, and it makes a pretty loud noise you can hear with the hood closed. The battery charging light is on on the dash. Is this the pulley - or the tensioner too? I have to order parts...

From reading the thread it sounds like you should replace the pulley, belt and tensioner all at once.

Here's a video of the tensioner. Idle speed bounces, it makes quite the noise. After a couple of minutes the idle speed comes up a little bit too.

For sure: Pulley only, or tensioner too (I guess just to be safe, but it's a hundred bucks!)?

(you have to click on it)

Sounds like my pulley is on the out too. My wife told me the car sounded funny at idle. Kind of a hollow "plasticky" sound from the passenger side by the serpentine belt. I noticed the tensioner bouncing around like so
http://www.youtube.com/watch?v=cXCdtGCRH5I

So in my shopping cart on IDI parts I have (for the BEW engine):
-pulley
-serpentine belt
-metalnerd tool set
-serpentine belt tensioner

That should do it, I think?

You got 'er. You probably don't need the tensoner... but it doesn't hurt either and then you're good with the entire system for another 250K.

I have a question - if your pulley is jamming up, could that overload and ruin the voltage regulator?


I just replaced my pulley, and the old one came out - and when it did, it freewheeled in the CCW direction like it was supposed to. In the car it didn't. Maybe I broke it free. In any case, it didnt sound good, like there wasn't any grease in it, just metal on metal. So I replaced it with a new pulley, took out the alt and all. What a fun way to spend 2 really beautiful days.


Guess what - it still bounces like before, maybe a little less, but it does, like in post #25. I am guessing - this is a regular motion, and not a 'bounce', as if controlled by something the ECU to increase load at the alt, because it isn't producing enough voltage, and I think that's what it is actually doing. I've figured that it's the voltage regulator since the running voltage is lower than the engine-off voltage. If you see the tensioner doing that, you probably need a new regulator or a new alternator.