Mechanical fan or Electric???

[Dannz71]

Gday trying to figure out what fan to use, mechanical or electric, and by mechanical i am refering to a straight up bolted to water pump, not a viscous unit.
Ive always found mechanical fans push more air but they can have a downside

I have a 350chev in my hilux and there is only about an inch between the water pump and the radiator, now i want to (for the better cooling) run a steel mechanical fan that is flush with the flange with the blades hanging back towards the engine, but im worried that if i cross a deep enough river then when the fan hits the water itl flex forward into the radiator and possibly punture it...

[zukmeista]

If doing a deep crossing you could slacken off fan belt to stop fan turning, obviously you would have to tighten it back up again on other side. Doesn't sound like you have room for an electric fan, and certainly not one that will keep the motor cool. Does the water pump have a long shaft? I changed to a water pump with a shorter shaft on my Rugger to give more room, not sure if that is an option with the Chev. Also might be worth looking into blanking off the mechanical pump and running an electric one, would give more room.

[slidenyo]

could use a flexalite fan,
blades will flatten out when they hit water,
we had a steel centred stainless blade one on dads rover.
went swimming heaps, had f all clearance, never hit...
http://www.flex-a-lite.com/belt-driven-fans.html

[derk]

could use a flexalite fan,
blades will flatten out when they hit water,
we had a steel centred stainless blade one on dads rover.
went swimming heaps, had f all clearance, never hit...
http://www.flex-a-lite.com/belt-driven-fans.html

not sure which one you were using but those flexalite fans are generally the last things you'd want, they fatigue and throw blades through the radiator and bend blades when they hit deep water and they usually aren't known for being big air movers when it comes to cooling

[Mattman]

I have done numerous deep water crossings with the engine fully submerged and not had an issue with my viscous fan.

Any reason why you won't run viscous?

Cheers
Matt

[derk]

Any reason why you won't run viscous?

Cheers
Matt

yep never seen one fit into a 1 inch gap

[Dannz71]

yea so i dropped the engine back in last night and turns out i have more like 40mm but yea not enough for a viscous hub, i could fit up to a 20 inch fan infront of the radiator if i cut out a bit of panel steel. but im intriged by the flex fan option.
i like the idea of a mechanical fan because they dont burn out or stop working way out in the bush, and the extra air they tend to push is a bonus

[Mattman]

A viscous hub with blades that are stepped back should work perfect.

Viscous hub allows the blades to stop when they hit the water.

Matt

[derk]

A viscous hub with blades that are stepped back should work perfect.

even with a 40mm gap a chevy viscous would work really well with a big hole cut in the radiator they are a pretty deep hub

[Heath]

I assume you are already running a short water pump. If not and you still have the LWP then the SWP will give you some extra room (of course then you have to muck around with spacing of other bits...)

[Dannz71]

yeah already have a swp, so the gaps not getting smaller, unless i cut out the radiator support but then itl start playing hell with the bonnet and bonnet catch etc, doesnt sound fun...

[Mattman]

I cut out my radiator support panel and removed the latch and ran bonnet pins. Put two strengthening ribs between the top support and the lower body section. Allowed the radiator to go right in.

Matt.

[ChurchurDan]

Mechanical fan
pros, will always be turning
cons, need to rev engine to get decent airflow, deflect in water and mud and sap horse power unless it is a viscous unit.

Electric fan
Pros, move rated volume of air all the time, can be switched off
Cons, need electricity to work, self destruct if running when they hit water or mud, you need to spend good money to get one they will move enough air.

Flexi fans, Don't go there they fly to bits without being provoked I would hate to see what happens if they hit water or mud and they don't move much air with revs up as they flatten out. Also the sap a lot of power.

My preference is always a viscous mechanical fan. If your going to see a lot of water crossings make up a quick release tensioner for the fan belt like the willys jeeps have.
Electric fans have gotten a bad rep recently as too many people have bought cheap ones and they were not up to the task. A good quality electric fan with a shroud will out perform a mechanical fan but they also use a lot of power and most 4x4's are already at the limit of available electricity and a fan sucking 20amps does not help.

[Dannz71]

Mechanical fan
pros, will always be turning
cons, need to rev engine to get decent airflow, deflect in water and mud and sap horse power unless it is a viscous unit.

Electric fan
Pros, move rated volume of air all the time, can be switched off
Cons, need electricity to work, self destruct if running when they hit water or mud, you need to spend good money to get one they will move enough air.

Flexi fans, Don't go there they fly to bits without being provoked I would hate to see what happens if they hit water or mud and they don't move much air with revs up as they flatten out. Also the sap a lot of power.

My preference is always a viscous mechanical fan. If your going to see a lot of water crossings make up a quick release tensioner for the fan belt like the willys jeeps have.
Electric fans have gotten a bad rep recently as too many people have bought cheap ones and they were not up to the task. A good quality electric fan with a shroud will out perform a mechanical fan but they also use a lot of power and most 4x4's are already at the limit of available electricity and a fan sucking 20amps does not help.

Cheers churchurdan for your input makes a good bit of sense.
Had a big mock up and remeasured eveything and decided a big electric fan was in order, HOWEVER for a big electric fan and shroud to work then im stil going to have a big interference issue with the water pump,
SO i thunk to meself, bugger it im sick of heat problems and decided once and for all to fix it good and proper, ditched the old inefficient mech water pump and i went out and bought a craig davies electric water pump, fan and controller.

So now il have a good constant flow of water and a good constant flow of air, reguardless of engine speed. also i did a few calculations and worked out that with this new water pump when the pump is at peak flow it will circulate the water every six seconds

so with a bit of luck all cooling issues should sussed, (il find out next week when i get my new bellhousing)