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Hi, I have all the stuff needed to change the timing belt and the water pump, the pulleys, seals, gaskets etc. The only thing I don't have is the tensioner spring. The person I bought it from told me that it is not normally changed since it does not usually wear out.

What is the consensus here. Would you change the spring or leave it.

I think people replace them. I reused mine but my motor was a low mileage motor and everything looked brand new.

Doing some more research I discovered that this spring is only used during the tensioner adjustment stage. The tensioner pulley is then tightened down and the spring ceases to do anything. The spring will see a constant tension and a temperature cycle. Is this able to alter the physical properties of the spring. Has anyone heard of a spring breaking or degrading.

it is a 2 bob item- if you go to Mazda in Ringwood the spares guy says they always replace them- why sweat on such minor items.

It doesnt contribute anything to anything except help set the tensin on the belt before you tighten the tensioner. The mazda book tells you how tight it has to be and how to test it so if you follow those instructions the spring is worthless.

Dann

x 2 with NitroDann. Relying on the spring to set tension is nowhere near as accurate as following original Mazda specifications.

Mazda wrote:Measure the timing belt deflection by applying moderate pressure (98N, 10Kg, 22lb) midway between the two camshaft pulleys.
Dellection: 9.0-11.5mm (0.35-0.45 in) at 98 N (10Kg, 22lb)

I just spoke with Essendon Mazda and apparently they are cheap but they don't have them in stock. The person in spare parts told me that the last time they sold one was in 2007. So it appears that even their service people don't really consider them important.

Mr Morlock, you are right they are very cheap. I would not hesitate to change it if there was even a small benefit.

Theres no small benefit, its to make sure the belt at least stays on for a week when the apprentice at the dealership changes it.

Dann

if you have all the pulleys etc the timing belt kit should include a new one.
though in saying that once the tensioner pulley is torqued its useless

As stated earlier Mada in Ringwood say the tension spring is an item to replace. They also said the idler and tensioner pulleys ( exxy) are replaced only if required ie the mechanic's call. The shop manual says for the spring -Tensioner and Tensioner Spring Installation Note
1. Measure the tensioner spring free length.
If not within the specification, replace the
tensioner spring.
Free length
59.2 mm {2.31 in.

Once again ill say that its only a failsafe. Your obviously now aware of the correct tensioning procedure, so you do not need one.

Dann

The spring doesnt actually give you the correct tension, the cam belt should only deflect downwards by 9mm in the middle between the two cam shaft pulleys when the tension is correct, you need to get this bit right and to do that involves pushing the idler in a bit further, then tighten the bolt. If that bolt came loose somewhere down the track, then the spring might save you from throwing the belt. the spring really does nothing from one day to the next. I wouldnt change it unless for some reason it looked bent or worn out of shape, and then I would be looking for the cause of that with some concern.