Attaching Clutch Fan

[HK1837]

I just measured a red HQ 253/308 one and it is 40mm front to back. So that square edged one also suits the same shorter pump, so as goat says it must be an A/C thing? Also HZ lists an air and no air pulley, the 7435189 pulley is the no air one (which is what i've got here, like 10 of them!) and 2812459 will be the 40mm square edged one for engines with air except for ADR27A engines with air which in HJ use 9942908. The 99 number disappears from HZ catalogue so there is just air (28 number) and no air (74 number). WB is the same as HZ for short water pump, and 2 x new 92 prefixed numbers for the long water pump, again air and no air. WB catalogue gives the pump lengths as 94mm and 110mm so the depth of the pulley in these will be 56mm.

Afterthought. I just checked the HX catalogue and it almost gives the game away. I reckon the round and square 40mm pulleys are different diameters, or the HJ 9942908 is a different diameter. The round one is 149mm across. This is what HX says:

7435189 - V8 no air.

2812459 - V8 auto engine with air with ADR27 (evaporative only ie canister etc as per HJ), V8 manual engine with air with ADR27A (evap and exhaust emissions ie normal HX) PLUS V8 with air cab chassis.

9942908 - 5.0L manual engine with air and with ADR27 except cab chassis (so again HJ style engine), V8 auto with air and with ADR27A except cab chassis.

So I reckon they are all different diameters, the A/C cars don't drive a fixed fan so the pump can be driven at a different speed, plus the 1-tonner involvement hints at this too as tonners generally have lower ratio diffs unless they were V8 with air then they had to have a 3.36. Just putting 2 and 2 together from this and hopefully getting 4, I think this means the 74 pulley is bigger than the 28 pulley. Not sure on the 99 pulley. Food for thought anyway!

The fact there are different numbes on WB for air and no air V8 also hints at a different diameter pulley. Blocker, I reckon that longer one you got is off a WB V8 (long pump) without A/C. The A/C one for the long pump will be the square edged long one.