Serpentine/Accessory Belt Tensioner v Idler Pulley

[MitchD]

Hi everyone

'07 2.8 CRD

Looking at replacing the pulley on the accessory belt tensioner. It is causing the belt to slide towards the radiator, and jump off one rib. There is a good amount of chirp as well.

What I can't seem to find info on anywhere:

Is the accessory belt tensioner pulley the same part no. as the idler pulleys (e.g. EP101?)

I'll be looking into a the full kit in the near future, just want to solve this now so I can drive in the meantime.

Cheers

[indiedog]

The tensioner pulley is a separate part, I don't think anyone replaces the pulley without replacing the tensioner. The chirp usually comes from the overrun decoupler pulley on the front of the alternator. If you look for a thread I started you will find the model numbers and they are probably in the CRD thread too. Take a look at that before you order anything.

[MitchD]

Thanks!

I had a chirp at idle that increased with rpm. Oddly after a short drive, the idle chirp disappeared but it would still at higher rpm.

Inspection showed me the belt had slipped off one rib on the pulleys either side of the tensioner and the tensioner pulley wasn't sitting in line (I think this is why the noise changed). I suspected it was just collapsed bearings in the tensioner pulley, but after removing it, the whole unit had failed and was sloppy between the fixed part and the tensioner arm, causing it to sit off centre with the belt pressure, ultimately causing the chirp in the bearings.

Replaced the tensioner with a dayco one from bursons.

All noises gone, happy days!

[glend]

Originally Posted by indiedog

The tensioner pulley is a separate part, I don't think anyone replaces the pulley without replacing the tensioner. The chirp usually comes from the overrun decoupler pulley on the front of the alternator. If you look for a thread I started you will find the model numbers and they are probably in the CRD thread too. Take a look at that before you order anything.

Indie, Mitch owns my old vehicle, and i had replaced the alternator and it's pulley/ decoupled just a few years ago (after the decoupler pulley started jumping on over run on a trip back from Qld.) I doubt the decoupled could be the problem in this case. It was interesting at the time it was possible to buy a complete new alternator with decoupled pulley attached, for not much more than the pulley itself (They are not cheap, and then you need the tool to remove it, or cludge up something).
I am trying to recall when I last changed the accessory belt tensioner, I think I did but it would be written in my personal maintenance log book (which it seems has disappeared after i gave it to the guy who originally bought the KJ off of me).
At least it has found its way to someone who will look after it, now.

[MitchD]

Couldn't be more happy with the KJ, and full credit to Glen for this amazing vehicle!

Alternator was in May 2018 or thereabouts, I've been through all the old threads working out what must have been in that black book. I'm keeping at the old owners to find it for me as it's invaluable!

In answer to my original question, in case someone in future looks at the pulley on the tensioner as I did and thought I could change it;

The accessory belt tensioner pulley is the same as the other two idler pulleys (which are covered extensively in other threads), but it is probably incredibly difficult to try and remove it while still on the car because it would be difficult to lock the tensioner in place to undo the bolt. My tensioner had failed and it is probably just worth replacing the unit for safe measure, and I say this because it is an "inspect and/or replace" item every 10,000kms which tells me it is something that wears out regularly enough.

[indiedog]

Originally Posted by glend

Indie, Mitch owns my old vehicle, and i had replaced the alternator and it's pulley/ decoupled just a few years ago (after the decoupler pulley started jumping on over run on a trip back from Qld.) I doubt the decoupled could be the problem in this case. It was interesting at the time it was possible to buy a complete new alternator with decoupled pulley attached, for not much more than the pulley itself (They are not cheap, and then you need the tool to remove it, or cludge up something).
I am trying to recall when I last changed the accessory belt tensioner, I think I did but it would be written in my personal maintenance log book (which it seems has disappeared after i gave it to the guy who originally bought the KJ off of me).
At least it has found its way to someone who will look after it, now.

Okay, didn't know that history. What a bonus to have the full history of the car available! The decoupler can be bought separately from Litens in the US for not much, don't buy it here. I put up details of who to contact for them a number of years ago. And they come with different fixings, mine was an allen key I think.