V6 Auxilary Belt Tensioner bearings U/S, How to save £170.

[windywatson]

Whilest replaceing the radiator & thermostat on my camper. I checked out the condition of the auxilary belts & tensioners as the underbody tray had to be removed to do the Stat. I found that the bearings in both tensioners to be noisey & needing replacement. Having had both tensioners replaced on my Tin top as part of the cam oil seal & cam belt change etc, I had the old parts to examine. On inspection I found that the tensioner pulley for the Alternator/steering pump had the bearing in it as integral part the plastic being moulded around it. So had to invest in a new one at £80 mazda genuine part. Intrestingly the new ones are now made of metal & the bearings can be pressed out if replacement needed.
The bearing in the tensioner for the water pump & air con compressor can actually be replaced. Saving you money, as these pulleys only seem to be available as a complete item at around £180.
However there are 2 very important points to bare in mind. One I have mentioned on here before, the bolt securing the pulley to the tensioner is a Left hand thread , get this wrong and as the casting is not that substantial you could destroy it. The second is that it is advisable to remove the tensioner from the engine to carry out the removal of the pully. This makes it easy to apply some heat to the back of the tensioner to aid removal of the bolt to ensure that you don't over stress the casting.
Below are photos to help with the description of my methods.

Tensioner removed on bench.

Center bolt, Left hand thread denoted by L on bolt head.

Rear view of tensioner, as can be seen casting is not that substantial. I applied heat to the back around the bolt which aided removal.

Having heated the pulley with a blow torch around its circumference making it expand. I was able to punch out the old bearing with a 27mm socket with relative ease. The bearing can only be pushed out one way as there is a shoulder on the back of the pulley that the bearing seats on.

This is the pulley turned over so you can see the shoulder that the bearing seats onto.

Here you can see the details for the replacement bearing I used. The bearing ID was easily found stamped on the old one. This one was an equivalent I found on internet, supplied by Simply Bearings.

I once again I reheated the pully & then used another socket 32mm to drive the new bearing into place. You can tell when the bearing has seated as you get a differant sound to the hammer blow when it can go no further. Once seated cool down the pully quickly to prevent any heat transfer to the bearing.

This shows pulley turned over, showing the bearing driven home onto its seat.

The reassembly is just a reverse of the dismantling proccess. My tensioner now refitted & working well.
Hope that this is usful info as it is a big money saver if you have basic mechanical skills.

Cheers.

[Bob]

Splendid info,really clear instructions and pics, thanks.

[Northern Bongolow]

i love a cheap fix me. great how too.