Outer Limits 4x4 Board

im currently haveing issues keeping the old girl cool ive got an aussie desert cooler radiator and ba thermos but im not to confident in how reliable eletric thermos are anyone got some suggestions?

Thermo fans are better than visco fans in my oppinion.
- more fan surface on the radiator (dual setup possible)
- an override is possible to turn them off for water crossing and turn them perm on for towing etc.
- they dont take much power of the engine

With BA thermos and a big radiator should be all fine with your chev v8.
Maybe your shroud around the radiator is missing (between front and radiator) or the radiator is blocked?
Could be the water pump as well or maybe air in the system.

Just a few general principles
1 You must have a shroud that fits tightly around the fans whether they be mechanical or electric
2 The shroud must be sealed where it meets the radiator so that there is no stray air going around it.
I personally am a fan(LOL) of viscous fans as the implied HP of one is far in excess of the HP of the electric fans . There are several reports on AULRO of people with electic fans replacing them with the old viscous after an overheat on sand or whatever.
I am not as sure as I used to be about the parasitic drag of viscous fans, as the force of air through the radiator will tend to push the fan a lot which will reduce the load on the engine. Of course at slow speeds they still drag, and drag a LOT if you are in sand on a hot day. BUT my 3.9 auto stayed at just under normal last weekend on Stockton, on dry sand in 3rd low pulling my camper at 4000RPM. The fan was outroaring the exhaust but boy was it pushing air.
I am familiar with electric fans having set up my Porsche 924 turbo which overheated with local air. The big difference was made when I got a genuine Aircon shroud from Germany, and fitted the existing fans to it.
BUT I had a few problems with relays which happened at the worst time according to Murphy's law.
Regards Philip A

Hi,

I have a 350 in a 74 RRC with the stock 3.5 rad and fake EL thermos (with slightly modded EL shroud). Been good since fitting the thermos 70k km ago. Previously had stock Chev fan and modded shroud. Current set up is waaaaaay superior crawling around on hot days, in traffic or elsewhere.

One fan is on all the time, the other on an adjustable temp switch that comes in when the gauge gets to 1/3 or 1/2 roughly.

If you are running on lpg a dud vac advance will raise the temp considerably, especially if the advance is coming from the manifold.

Could be no blades left on water pump.

The shroud is crucial, as the fans run with a much closer tolerance to it compared with a fan running off the motor and stock shroud. New fake EL fans in a shroud were only $200. (Corio Autoparts). The shroud is a very near direct fit behind a RRC rad.

My motor has over 400,000 on it and is getting a little tired. On a stinking hot day @ highway speeds the temp gauge will get up to half, but if I stop and just let it idle the fans will pull the temp down to under 1/3 in less than a minute.

cheers, DL

[quote="Philip A"] There are several reports on AULRO of people with electic fans replacing them with the old viscous after an overheat on sand or whatever.
[/quote]

At slow speeds my experience is that thermos would way outperform the old fixed fan in my POS. The old shroud was a pretty good fit around the fan.

cheers, DL

At slow speeds my experience is that thermos would way outperform the old fixed fan in my POS

But how old was the viscous hub and was it stuffed?
A lot of people compare an old stuffed viscous with shiny new electrics.
Do you have aircon? and have you also got condenser fans?

I guess I am influenced by most HD 4wds still have viscous fans and in fact a Prado diesel ( last model) only has a viscous fan and it blows enough at low revs to be effective for the aircon. I am pretty sure a 200 Cruiser also has a viscous and certainly 38A and AFAIK L322.
If electrics are effective enough , surely they would all go there seeing the fuel economy benefits etc.
Regards Philip A

Could you put an engine fan on and have a 16inch dc fan on the front of the radiator or would they fight?

[quote="Philip A"][quote]At slow speeds my experience is that thermos would way outperform the old fixed fan in my POS[/quote]
But how old was the viscous hub and was it stuffed?
A lot of people compare an old stuffed viscous with shiny new electrics.
Do you have aircon? and have you also got condenser fans?
[/quote]

Hi Philip,

Had the ultimate viscous hub; i.e. solid mount to the water pump. No aircon.

The point I continually try to get across is that thermos will both be on and roaring when the engine temp goes up, irrespective of road or engine speed. Viscous fan speed is somewhat related to ambient and engine temp via the viscous hub, but the max speed of the fan is limited by engine speed at any particular time.

Twin thermos are way more effective for cooling my POS at low road and /or engine speeds than the old set up.

BTW, I wouldn't be surprised if some engine mounted fans are just a hangover from old design / assembly procedures.

350 Rangie........... sounds like you don't have a shroud at all! Going to be hard to have any effective set up without one of some description.

cheers, DL

I run AU fans behind my radiator and they cool my engine very well. THe shroud is almost a perfect fit on a Rangie radiator.

Recently whilst on the dyno we left the fans turned off and the engine overheated.

We then ran the car on the dyno with the fans on but the dyno fan off and it remained cool.

This was on runs with well over 200rwkw and we gave it a flogging.

I would never go back to a viscous fan.

I also have a large heat exchanger in front of my radiator for my water 2 air intercooler, so the fans were doing it tough..

Cheers Zuffen,

Different strokes for different folks, but your input on the thermo 'debate' is on the A list.

The only crew who doubt how well they work are ones who've never seen how well they work in real life, especially in modded RRC's.

DL