On the motorway today, my Skoda Superb 2006 displayed the battery light and I lost power steering. I had to call the AA and was told that the Auxiliary Tensioner pulley had broken, which had stopped charging the battery and lost power to steering, water pump etc.

 

Would anyone have an idea of cost to get it replaced at a garage?

It is best to replace the whole tensioner if it is old enough that the pulley has gone, the whole assembly only has a service life of 60,000 miles according to the manufacturer. I paid about £75 for the genuine INA part. Belt is about £10 for Conti belt. You have to ask why it failed. Often they can fail because the alternator pulley has failed. That pulley is between £30-40 for genuine INA parts. I am sure you can get cheaper bits if you want to do the job twice...

Obviously the above plus labour. It isn't too big a job, I would have thought a garage could do the lot in an hour and half easily.

It is best to replace the whole tensioner if it is old enough that the pulley has gone, the whole assembly only has a service life of 60,000 miles according to the manufacturer. I paid about £75 for the genuine INA part. Belt is about £10 for Conti belt. You have to ask why it failed. Often they can fail because the alternator pulley has failed. That pulley is between £30-40 for genuine INA parts. I am sure you can get cheaper bits if you want to do the job twice...

 

Thanks, I've decided to get the timing belt changed and serviced at same time, which together is costing £290.

Sounds very cheap. As I say check why the pulley failed as quite often people go through a couple of tensioners before realising that the alternator pulley is killing them...

You getting the water pump done at the same time? I think I paid around £280 for my last cambelt and waterpump change at an independent.

Hmmm the battery light came back on again, and I thought the tensioner had gone again, but been told its the alternator that's gone this time. Could be what possibly caused the tensioner issue in the first place?

Did you do get the pulley done, or just the tensioner?

 

If you didn't do the pulley, then as per previous post, you have to ask why the tensioner failed.  It could have been old age, or it could have been broken by a bad pulley.  Lots of people go through a couple of tensioners before fixing the cause, which is the pulley (in many cases).

 

To test the pulley you need to take the alternator belt off (using a long spanner on the bolt head cast into the tensioner to let the belt off).  You then lock the rotor of the alternator using a non-metallic item (I use a small plastic pry tool).  You then try and turn the alternator pulley.  You should find the pulley spins nice and freely in one direction, and locks solid in the other direction.  They can fail both ways - either locked permanently, or free wheel in both directions.  Mine would switch between the two modes.  Both are bad.

I should add, some people will change the whole alternator when it is just the pulley. This might or might not be a good idea depending on the quality of alternator which will be fitted in its place.

You can test the alternator sprag pulley in-situ. With the engine stopped, take a small probe and try to move the internal fan in the alternator in each direction. It should be reasonably free anti-clockwise and solidly locked clockwise as you look at the alternator, Be careful not to damage the enamel on the stator windings.

 

A defective alternator pulley will nearly always destroy the tensioner. At the second timing belt change, it's worth carefully removing the seal in the tensioner bearing and repacking with grease. The old grease will be dried out and useless.

 

A further cause of tensioner failure is the losss of the "O" ring on the long tensioner pivot bolt - usually by the dealers when changing the timing belt. It is put there to damp the vibration in this long bolt which can cause failure at resonant engine speeds. Most dealers seem unaware of its function - it's on the parts list.

 

rotodiesel.