Aux Belt Tensioner

[chromedome]

I could not find this one in the FAQs.

 

My aux belt tensioner "chatters" when the engine is running from cold, after a few seconds the chattering stops as the engine starts to run smoother.

 

Is this a sign of imminant failure or should I get it changed?

 

Thanks in advance for any advice given.

Edited May 4, 2012 by chromedome

[daddyfixit]

if you watch it, is it bouncing up and down a lot ??? if so it sounds like it is getting too weak to keep belt tensioned.

[gregers]

you sure the noise is the tensioner and not the pully wheel?

[chromedome]

I think it's the tensioner, large aluminium lump. When cold you can see it really shaking around and you can stop the chattering sound by simply holding it firmly. When the engine running has smoothed you can still see it wiggling about a bit and now you get the odd chirp (I wondered where the budgie went :rolleyes: ). I looked at the alternator pully and it appears to be running true.

 

Thanks for the input.

[seatkid]

I think it's the tensioner, large aluminium lump. When cold you can see it really shaking around and you can stop the chattering sound by simply holding it firmly. When the engine running has smoothed you can still see it wiggling about a bit and now you get the odd chirp (I wondered where the budgie went :blink: ). I looked at the alternator pully and it appears to be running true.

 

Thanks for the input.

I think its still likely to be a seized alternator pulley. On certain engines (IIRC those fitted with a DMF, which have a light main flywheel), at low speeds/ cold engine, the crankshaft speed is not constant during a revolution. Because of the large inertia of the alternator rotor, VW introduced a freewheelling pulley to stop it exaggerating the variation in tension of the belt during each revolution. The result of a seized freewheel being that the tensioner cant cope and so it jumps around.

 

Do the test on the alternator pulley first before changing the tensioner or roller. Remove the belt use something to hold the rotor, then check the pulley is free to rotate in one direction and drives the rotor in the other.

Edited May 4, 2012 by seatkid

[chromedome]

I have ordered the alternator pulley from GSF on-line. On mine it looks like there is some kind of cap on the front of the pulley, does this need to be prised off to reveal a locking nut? Also is it a left or right handed thread and am I right in saying it is very tight.

 

By the way I have also ordred the Sealey tool for removing the pulley.

 

Sorry for all the questions, it's been a while since I've done any home mechanics. Give me a Cortina any day. -_-

[seatkid]

Sorry for all the questions, it's been a while since I've done any home mechanics. Give me a Cortina any day. :blink:

Oh yeah... those days everything seemed so simple and so much room........ :)

 

I take it you tested the pulley then and satisfied yourself thats the problem?

 

From what I've read it seems that getting the pulley off can be quite a job. Local indie quoted

[chrispb123456]

My local Alternator/Starter repairer will change over the pulley FOC if purchased there.

 

[gregers]

follow the instructions on here on replacement,i did and managed it,AND THATS AMAZING IN ITSELF.:lol:

[chromedome]

I will let you know how I get on, I'm sure someone on the forum said it only took him ten minutes.

[chromedome]

I chickened out :wacko: and got my local garage to do it. The auxilliary belt was replaced at the same time.

 

The result.............a smooth running system and no chattering.