Cam belt tensioning

[smudgyrover]

Hi

I am about to replace the cambelt on my 300Tdi Disco. The workshop manuals say the tensioner shpould be tightened using a dial type torque wrench with a range not exceeding 60 Nm. Problem is I cannot find one of these to buy - all the dial type torque wrenches I can find have a range to at least 150 Nm which would obviosly not give a very accurate reading at the 14 -16 Nm range needed to tension the belt.

Question is, how do the rest of you get over this one? Is there a secret supplier of these torque wrenches who hides his light under a bushel? Or do you just guess? Or bodge it some other way? Any advice would be greatly appreciated!

[cipx2]

I've been using a 150 Nm one and it's fine. All you need is a good eye and a steady hand.

Or use the poor man's (or bushman) torque wrench: a plastic bottle filled with some water hanged on the end of a regular wrench (do the math for how much water depending on the length of the wrench) - which doesn't require good eyes or steady hands, it's free and readily available.

[BogMonster]

Ours at work is 30nm IIRC

Google that http://www.google.co.uk/search?hl=en&s...earch&meta=

[dooroy]

As cipx2 says you can rig up your own ' torque wrench' - I have used a kitchen scale in the past when the required figure was low . A bit fiddly but not much point in buying a wrench for a once off job as in my case .

Or else you can hang a known weight on the end of a bar - at least it will be accurate . As you say a wrench which goes up to 150 ft.lbs. will probably not be very accurate at say 10- 12 lbs .

I once used a 56 lb weight on the end of a 6 ft bar to tighten the crankshaft pulley bolt in a Transporter to the required torque of 336 ft.lbs. I was amazed at how tight this was .

[lrnick]

This mite sound silly but instead of working out how long the bar your using and the weight you need to hang off it why not buy one of those cheap torque wrenches (the one with a poniter on it) and use that! they cost around 10-12 quid.

I know there not great but alot better than try to second guess filling a bottle with water and working out the length of the bar your using it on etc.

This type i'm talking about.

[BogMonster]

I've got one of those at home, a Draper one IIRC

[JimAttrill]

I do it by 'feel' now, having done a few. Dial torque wrenches are very expensive. I have used one of those cheap things as shown above as well.

[dooroy]

I used to have one of those also - until the pointer fell off .

Accuracy seemed to be of concern here - these are relatively cheap tools and I don't think the manufacturer would consider them to be accurate all across the range .

I have changed many belts on diesel and petrol cars and do as Jim says - being able to turn the belt about 90 degs for example on its longest run . And have never had a problem .

The first time I read in the manual about changing the belt in a Disco I thought the adjustment method described was OTT.

[smudgyrover]

Many thanks for all the advice guys - it basically confirms the conclusion I have come to - the workshop manual is no doubt the 'correct' way to go about it but with a little bit of ingenuity and common sense there are other ways of getting over the problem.

I think I am going to use a combination of bottled water, Jim's 90 degree test and 'feel'! I have two cambelts to do - my own and my son's (chip off the old block y'know) and I will post my experience once we have had a chance to see if it works out.