Water pump belt - twin setup.

[shampooefficient]

My understanding of the twin pulley system is that you use the shims to pack the two halves of the water pump pulley - less shims to make it tighter, more to drop the belt into the V.

Trial fitting before I put the engine in, even with no shims the water pump belt was very slack. Was stamped up as 6x100 V belt. Do I assume a new belt will be tighter or is there something else I need to look at, adjustment wise?

[muttleypup]

A new belt will likely be tighter, AVX 10x 600 'should' be the one you need. If you're fitting it with the engine out I think you'll struggle to get the belt to sit properly in the pulley and this is probably why it's loose. What works for me is to fit the belt, tighten the pulley bolts up and then turn the engine over on the starter, or very briefly run it. The belt with ride up in the pulley taking up the slack and then retighten the bolts. The shims are obviously guess work to how many you need but maybe start with 4 and work up or down from there.

[shampooefficient]

Aha! I suppose a fatter (10mm) belt will also quite naturally sit higher in the V of the pulleys.

I'll be getting a full service kit and putting it all together next week and will follow your method - many thanks!

[muttleypup]

The belt size you put, 6 x 100 doesn’t sound right, thats why I said 10 x 600. Just come actoss my spares and I have 6 x 100 on the alternator, 6 x 643 on the water pump. If you can’t read the code on your old belt try a local v belt supplier, they’ll be able to measure/match it and saves messing around with various belts from motor factors etc