Thread: Puma Viscous Fan Spacer? Improved cooling?

Potential downside I can see is fan blades coming in contact with radiator. Remember the factory has been building these for quite a while now. Not that they always get it right but I have had the fan blades get sucked into the radiator on a water crossing that left us immobile for 3 days in vic high country , no stress but it could have been.

I haven't looked at a pehwma engine,but I assume the fan sticks out slightly on the engine side of the shroud.
There is a reason for this,the engine will drag the maximum air thru the radiator.Start shifting it forward and it will start dragging air from the engine side lowering the cooling efficiency.
Andrew

Apparently flat bladed / ended fans should be half in / half out of the shroud for max efficiency because a lot of air actually comes off the tips.

Someone posted this info on aulro recently.

DL

most thermo electric fans are very close to the radiator fins and are structured very differently. vis...no tips small thin multiple blades enclosed in a ring...

I wonder if the engine fans being susceptible to for/aft engine movement are set back in a kind of compromise position to avoid hitting the radiator in sudden deceleration

Naaah. Thermo fans have the ring to create an 'end plate' effect that stops the air coming off the tips. The air can only go out towards the engine.

That's why they are inside the shroud. Someone on the forum explained why plain / flat tip blade fans are half in the shroud just because of the aerodynamics a few months ago.

cheers, DL

Maybe I'm misreading this, but isn't the OP saying move into shroud = further away from radiator?

Although both the Defender TD5 and TDCi (puma) use the same viscous fan assembly, unlike the TD5 that has the fan close to the radiator, the TDCi placement is just about half an engine bay away and has a long shroud made for it. I think as others have mentioned (fan position to shroud edge), you would then need to mod the shroud to get the fan to sit in the same position in relationship to the edge of the shroud.

IMHO.... I see this as a pointless exercise and highly doubt any cooling benefit.

Regards
Daz

The only gain would be the heat from the radiator would warm up the viscous oil slightly quicker and the fan would operate earlier than designed, in theory it would cool things earlier as advertised.

I looked at the spacers when I spoted them last year and decided not to do it for 2 reasons.
-Ideally as has been stated the shroud should be modified(trim shorter) to maintain best air flow available.
-It would also add more load to the shaft and the bearing supporting the fan.


If there is a concern of heat build up on slower hard work the air conditioner fan could be modified to stay on, I've done this to limp vehicles home with faulty viscous couplings.