Timing Belt Retensioning

[d7ve_b 44 1 Cars]

Hi All,

 

Yesterday I finally completed my first timing belt change (including new tensionser/waterpump/aux drive belt), woohoo me! Anyhoo the haynes suggests that after running the car up to temp I need to let it cool and then loosen the tensioner (spring loaded version) and re-tighten. Is this necessary/do people see a difference after doing so?

 

I know your probably thinking I'm a lazy git (which I am) but I just need some confirmation/motivation to get out there and get under it again!

 

Muchos gracias!

 

Dave.

[Mikey S 29 1 Cars]

Hi All,

 

Yesterday I finally completed my first timing belt change (including new tensionser/waterpump/aux drive belt), woohoo me! Anyhoo the haynes suggests that after running the car up to temp I need to let it cool and then loosen the tensioner (spring loaded version) and re-tighten. Is this necessary/do people see a difference after doing so?

 

I know your probably thinking I'm a lazy git (which I am) but I just need some confirmation/motivation to get out there and get under it again!

 

Muchos gracias!

 

Dave.

 

me personally, ive never needed to retension them. u set the tension, turn it over by hand twice then recheck it. your good to go if its ok after that.

[ljenkins22 0]

me personally, ive never needed to retension them. u set the tension, turn it over by hand twice then recheck it. your good to go if its ok after that.

 

i would agree with pugger, i work in a garage and only ever turn over twice by hand, seems to do the trick never had one go wrong

[smithy 1]

ignore that bit i have done loads of belts over the years including v6's and scooby flat fours always change the whole lot tension up and turn by hand 2 revolutions and recheck tension then.

[SurGie 54]

I think some of the Haynes instruction ways are for their own extra safely precautions, they fully break and fully re-build every car then publish their books on these cars AFAIK. I guess they also given instructions from Peugeot themselves.

[kyepan 291]

The reason they say to run the car up, is because the belt has an initial amount of stretch. same reason you put on new drive belts, run them then tweak them up.

 

This is also why auxiliary belts that have been run for five minutes or more have different deflection test loadings (on my mx-5) than new belts.

 

Not doing this will mean the belt is not tensioned perfectly, and therefore cam timing may be slightly out.

Practically speaking it's an arse to run the car for five minutes with the covers off, as you would have to refit water piping, and refill the system.

 

Hope this helps

 

J

Edited May 2, 2011 by kyepan

[SurGie 54]

I will be doing the cambelt on mine with the engine out.

 

Would it be a good idea to use a starter motor with a battery to turn the engine round a good few times ?

 

Cheers

[Tom Fenton 1,548]

There is no real need to retension, as said turn over a couple of times by hand, check tension then box it up.

 

I don't agree with comments re: stretch, the flat profile belts don't stretch and if you cut an old one in half you will see why.

However the poly-vee belts do need retension after a short time when fitting a new one, this is due to the rubber coating on the vee's bedding into the pulleys on the ancilliaries, hence the belt becomes less taut after a bit of initial running, but not due to stretch of the fibres in the belt construction.

[kyepan 291]

There is no real need to retension, as said turn over a couple of times by hand, check tension then box it up.

 

I don't agree with comments re: stretch, the flat profile belts don't stretch and if you cut an old one in half you will see why.

However the poly-vee belts do need retension after a short time when fitting a new one, this is due to the rubber coating on the vee's bedding into the pulleys on the ancilliaries, hence the belt becomes less taut after a bit of initial running, but not due to stretch of the fibres in the belt construction.

That makes more sense, so your saying the inner surface is compressing, but the belt length is the same and not the belt itself stretching.

Edited May 3, 2011 by kyepan

[d7ve_b 44 1 Cars]

The general consensus seems to be that retensioning may not be necessary (but obviously the responsbility lies with me to decide).

 

Many thanks all.

[smithy 1]

The reason they say to run the car up, is because the belt has an initial amount of stretch. same reason you put on new drive belts, run them then tweak them up.

 

This is also why auxiliary belts that have been run for five minutes or more have different deflection test loadings (on my mx-5) than new belts.

 

Not doing this will mean the belt is not tensioned perfectly, and therefore cam timing may be slightly out.

Practically speaking it's an arse to run the car for five minutes with the covers off, as you would have to refit water piping, and refill the system.

 

Hope this helps

 

J

 

timing belts do stretch slightly but not after a few minutes of running,on a belt that has done its life miles you will find it will of stretched by only a few mm and certainly nothing that would justify a retension or cause the cam timing to be out.

 

for cam timing to be out by a tooth the belt would need to stretch 8-10mm.

 

as said a couple of revolutions by hand and then recheck tension will suffice.