Thread: Thermatic electric fan conversion

The wheel being reinvented.
Over many many years owners of RRCs and D1s have found that while electric fans work well in on road driving , once in sand or mountain tracks on a hot day they are inadequate.
I recall seeing many years ago that the viscous fan when engaged used about 8BHP .
if you convert this to amps it comes to hundreds of amps.

The fans on an RRC are to cool the aircon evaporator and without them working the head pressure gets very high. I recall mine died once in Kununurra and the starter would not turn the engine .

If your RRC runs at 94c there is something wrong. Either the thermostat is the wrong temp, the radiator is blocked , the viscous fan is stuffed, or you have a head gasket leak. The VC also cuts fully in at about 94C so it should not drag too much power at lower temps.

BTW a 300TDi fan and VC will fit with a bit of blade trimming and cools better than the stock white fan.
Regards Philip A

In my case I will be doing this to a D3, so if they differ at all with an RRC in this regard I dunno...

I can imagine the viscous fan uses 8 BHP, because when on (90% of the time on mine), the car feels much less powerful and acceleration is slow and noisy too...

Id be curious as to the air flow in CFM the viscous fan produces, as the biggest Davies Craig fan pumps out about 2100CFM....

In my case I will be doing this to a D3, so if they differ at all with an RRC in this regard I dunno...

Hasn't the D3 got an electrically controlled VC?
I seem to recall seeing a wire going to it in photos.
If that is true I would imagine it is controlled by the ECU determining when it should be engaged.

I guess my response is that a 200 Cruiser has a VC, a D3 has a VC, a Prado has a VC.

Do you really think given the extreme reliance placed on fuel economy that both companies would fit a VC if they could get away with electric fans?

I just went to the shops today in my daughters 2014 Challenger which has a VC. The outside temp on the dash was 44C at Kincumber . The temp gauge didn't move although we do know they are insensitive. Now 44C is not quite as bad a Saudi where you can get over 50C but it is up there with the worst in the World, and halfway up a sand dune on a 40C day is not a good time to find your electric fans are not doing the job.

You make some good points, I would prefer to keep the VC fan. Its just the power loss is pretty crazy.

Perhaps the clutch is stuffed, not sure how I would diagnose that.
More often than not the fan is running. Only at the lowest of ambient temps does it not run (in summer, its never low enough), so acceleration feels like I'm driving a Defender.
Maybe the thermostat is stuffed also, doesnt come on early enough perhaps....

Is there fan upgrades you can do to the D3? But a flex-a-lite on for example, that 'reportedly' improve airflow, efficiency, etc....

Originally Posted by specwarop

Perhaps the clutch is stuffed, not sure how I would diagnose that.

An easy way to tell is when the engine is hot and your fan is running try to gently stop the fan with a rolled up newspaper.
If you can stop the fan it is a pretty good indication that it is stuffed

Originally Posted by specwarop

You make some good points, I would prefer to keep the VC fan. Its just the power loss is pretty crazy.

Perhaps the clutch is stuffed, not sure how I would diagnose that.
More often than not the fan is running. Only at the lowest of ambient temps does it not run (in summer, its never low enough), so acceleration feels like I'm driving a Defender.
Maybe the thermostat is stuffed also, doesnt come on early enough perhaps....

Is there fan upgrades you can do to the D3? But a flex-a-lite on for example, that 'reportedly' improve airflow, efficiency, etc....

Just remember, that power has to come from somewhere and assuming the clutch is working properly, then its only running because it needs to.
Are you certain the engine is running properly? Ignition timing, O2 sensor, map & maf sensor, running lean?

I think so, I haven't the means to tell without visiting a mechanic.
Any minor issues that is.

You've got something similar to this on your 4.0 V6. Its where I'd start looking.

BorgWarner Visctronic® Fan Drive for Commercial Vehicle Applications - YouTube