Thread: Thermo Fan vs Viscous Fan v6.023.455

Been running twin 16" spal 3000cfm fans on a purpose-fabricated shroud, with a derale pwm controller for about 15 months, since the viscofan destroyed the radiator (fatigue cracking on the alloy retainer)

Not cheap, but it was cheaper than a new Shroud, fan, and clutch hub. Certainly cheaper than the consequences of another cooling system failure.

No issues.

Progress report. As I mentioned my intent in a previous post below, I tried a different switch TFS 135 in the thermostat body TFS135 - Thermo Fan Switches | Tridon, it switches on at 92º and off at 87º. Had it running for a couple of weeks on a commute and through the city (though far from bumper to bumper traffic). What I found is that as the fans cool so quickly, the on at 92º is not a problem - but the 87º off is the key, as its right around the fully open temp of the thermostat, the fans aren't trying to constantly cool below the point where the engine is running at optimum heat. The fans are off way more now, and only come on briefly when stopped after driving like exiting the freeway or similar. The temperature is generally more steady and constant. This is sure to change in summer, but its a good start.
Fuel economy is a tad better, got 16 per 100 over 300km including a bit of town traffic on the last tank.

I guess this story changes if you have the 82º thermostat where the TFS 109 might be better? Can't say, but that seems too cool for economical running.

Thanks for the update.

You might find the system will work better if each fan is switched independently, i.e. different temp switches for each.

Get to know how it's working on warm days first so any changes you make are well informed.

cheers, DL

I run two fans on my 110 with a 3.5v8. Each fan has its own dedicated relay.
In terms of controlling the fans, I bought one of those temp controlled digital thermostats. This allows me to change
temp and also handy having a display showing the temp sensor. You will probably find these are even cheaper than what
the likes of Supercheap sell.

The sensor for the temp is fitted externally between the radiator cores nearest the water entry. I have fans kicking in at 81 and off at 75.
Whilst this setup has worked well on the road, the fans struggle to keep up off road in dry sand, so i feel i am going to have to make changes
in the future.

Fan controller is the grey unit, it has its own on board relay rated at 10amp, which will be powerful enough to switch on the cooling fan relays
20150913_142646.jpg20180105_192302.jpg 20160103_192150.jpg

at one stage in my td5 D2, rather than replace the viscous fan which was failing , I locked it.

in the locked state it produced too much fan cooling and on anything but a warm day, the engine wouldn't get up to thermostat opening temperature.

so I just put a 2nd hand one in , all good.

the cooling system on a td5 D2 is a rippa so unless you have issues leave it alone. if the viscous fan fails , like mine did ,replace it. if the thermostat fails , replace it. keep it original , it wont let you down.

Originally Posted by Landyv8

I run two fans on my 110 with a 3.5v8. Each fan has its own dedicated relay.
In terms of controlling the fans, I bought one of those temp controlled digital thermostats. This allows me to change
temp and also handy having a display showing the temp sensor. You will probably find these are even cheaper than what
the likes of Supercheap sell.

The sensor for the temp is fitted externally between the radiator cores nearest the water entry. I have fans kicking in at 81 and off at 75.
Whilst this setup has worked well on the road, the fans struggle to keep up off road in dry sand, so i feel i am going to have to make changes
in the future.

Fan controller is the grey unit, it has its own on board relay rated at 10amp, which will be powerful enough to switch on the cooling fan relays

I like the controller set up! Where did it come from?

I think your problem in the sand might be due to the fans and shroud.

The blades on the EL fans are curved and have a ring right around the tips which acts as an end plate, i.e. air can't spill over the tip ends where all the action is.

The curved blades are way more efficient than straight and the shroud is sculpted to scavenge air through the whole radiator, not just where the fans are.

cheers, DL

This is really interesting about running the fans at 92. I think my fans are 86/92 (series/parallel). I don't mind if they idle away at low speed if not required. They are moving a small amount of air through the engine bay and are completely silent (without over-cooling it).

seeya,
Shane l.

Originally Posted by 350RRC

I like the controller set up! Where did it come from?

I think your problem in the sand might be due to the fans and shroud.

The blades on the EL fans are curved and have a ring right around the tips which acts as an end plate, i.e. air can't spill over the tip ends where all the action is.

The curved blades are way more efficient than straight and the shroud is sculpted to scavenge air through the whole radiator, not just where the fans are.

cheers, DL

The controller came from a local auction site (Trademe) however they sell them on aliexpress, ebay etc for less than $20. Just make sure you get the correct voltage, as they do 24v and 240v from memory too.

From what i was reading, and you know what its like with info on the internet, the curved blades were designed to reduce radiator fan noise but its at the sacrifice of cfm. Straight fan blades
produce more cfm but create more noise. (however, like i say that's what i read on the internet)
The issue is worse when off road and in convoy with headlights on with high rpm and low vehicle speed. Somebody did bring up a good point that made me stop and think and that's, how many 4x4 out there do you see
from factory running electric fans.

Having said that for the sake of $80 for a falcon cooling fan assembly, its probably worth a shot.