Tensioning of water-pump belt (diesel engine)

Post by **brookie** » 11 Jun 2007, 15:32

I need to tension my water-pump belt on my AAZ (diesel) engine. Fairly straight forward you would think but can't for the life of me see how it's done. When I replaced it last year there was no need to tension it anymore as when I did the pulley bolts up it tightened the belt up nicely.
One piece of info I read about doing this job says remove spacers between the 2 halves of the water-pump pulley thereby making belt ride higher on pullies and therefore tighter. However, I don't have any spacers to remove

Another diesel hand book says the same belt drives the alternator and the water-pump (driven from crank pulley) This might be correct on some diesels but not on my AAZ as I have separate belts.
The alternator belt tensions by pulling the alternator away and then tightening a pinch bolt but there is no option like this for the pump-belt as the pump is fixed.
I'm pretty sure the belt is not stretched out of limits as it's only 12mths (3000 miles) old

The belt is 10mm x 643mm which is what JKampers supplied/specified.
Should I try and fit a shorter belt or does someone have an idea how to remove this slack?

Post by **syncroandy** » 11 Jun 2007, 17:26

Perhaps ask on the alt. engines section ? Folk there may be more familiar with non-standard stuff.

Post by **andysimpson** » 11 Jun 2007, 18:24

any chance of a pic of your setup. Are you using AAZ pulleys or JX.

Post by **henry martin** » 11 Jun 2007, 21:08

for the use it might be,

You apparently quite right on the spacers, My old 911 has the same arrangment.

I recently put van in for a a squeeking fan belt at which point they swapperd the pair out, as they were halfway there,

and he pointed out the spacers/shims

Post by **Other-Power** » 11 Jun 2007, 21:57

Belts are like £4 each, change urm its not worth the possible hassle not changing them could do!

Post by **thenaylortribe** » 12 Jun 2007, 17:10

strange...my AAZ has a sprung loaded alternator belt tensioner

Post by **brookie** » 12 Jun 2007, 20:06

Yep, I know they're cheap so I'll go ahead and get another 10 x 643 belt tomorrow and try it. I'd be surprised if it had stretched in such short time though. I think I have the JX pulley set-up as it was originally a 1.6td JX (before I had it).
Basically crank pulley drives water-pump via this 643mm belt. Then the alternator is driven by a 600mm V belt from a second pulley mounted on the water-pump.
All looks very basic and straightforward, hope there's someone out there who's actually had success tensioning up this pump-belt and could let us know!

Post by **peasant** » 12 Jun 2007, 20:23

On the jx its done via shims on the water pump pulley.
Basically the width of the pulley is variable and by adding or removing a shim you change its inside diameter (the flanks are conical, not straight).

Pain to do, pain to get at and difficult to get right ....that's why I usually leave that job to a mechanic

Post by **Other-Power** » 13 Jun 2007, 06:22

I have always put these belts on with a screw drive and the starter motor. stick the screw drive in behind the pulley in such a way that when you turn the engine over quickly it will pop the belt of. Then just do the reverse to get the new belt on.

I know its not ideal and may do damage, but with consideration and an appropriate sized screw driver it will save you a good hour of oil mucky work!

Jon

Post by **brookie** » 13 Jun 2007, 18:48

My prob is not getting them on and off Other-power, it's tensioning the s**ing thing! Must say though your method orf removal/fitment sounds a bit lethal! Careful you don't drag the screwdriver between your cam-belt and a pulley

Cheers for responding though!

Post by **Other-Power** » 13 Jun 2007, 21:18

The technique is to have the pulley already tensioned with the shims prior to putting the belt on. I found today that you can just do it without screw drivers for getting them on.

Really hope this helps, im not the best at explaining but i hope this helps you

Jon

Post by **wullie_t25** » 13 Jun 2007, 21:35

Im doing my timing belt at the min and was trying to figure this out aswell.

Cheers for the post mate, think im gona go with a new belt, only has to last me till end of the year then im changing engine!

Post by **Other-Power** » 13 Jun 2007, 23:12

Engine rotates anti clockwise

get the belt on the water pump pulley first

get the belt on the top of the engine pulley and tension

turn engine over once

Belt should pop on

Dont forget the alt. belt needs to be put on prior to the pump belt

do the same for the alt. belt of the pulley belt.

Jon

Post by **Mick & Tracey** » 14 Jun 2007, 08:03

Just about to do this on mine today (if it stops raining).

Like you, I couldn't suss it at first, but am told that the water pump pulley has shims (like a bay generator pulley).

Just undo pulley (ha, ha - access looks very hard and it's held by three allen bolts - apparently trick is to put van in gear, squeeze belt together to tension and avoid pulley turning, whilst using your other hand to apply enough force to undo the the allen bolts).

Shims (big washers) should be visible on outside of pulley.

Principle is fine, access looks a like a bugger, but I'm used to bays and still trying to understand what I've got myself into with all this 25 stuff!

Post by **andysimpson** » 14 Jun 2007, 12:31

Other-Power wrote:Engine rotates anti clockwise

get the belt on the water pump pulley first

get the belt on the top of the engine pulley and tension

turn engine over once

Belt should pop on

Dont forget the alt. belt needs to be put on prior to the pump belt

do the same for the alt. belt of the pulley belt.

Jon

All vw engines rotate clockwise

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