Happy New year to all members!
I am currently investigating the possibility of fitting electric fans to my S3 jag. The yellow fan has cracks radiating out from the center and I'm not sure that it's long for this world. I have sourced a couple of fans from a Ford Falcon (Australian car) and am trying to work out the best way to control them. I know Grant Francis has done this mod a few times so am hoping he may chime in. By my way of thinking there are at least 3 ways of doing this. I can wire them in so that they are just on when ever the car is running or I can wire them up with a switch that will allow them to be turned on manually ( not really desirable if you are not watching the temperature gauge ). Another way would be to fit some sort of temperature sensing switch to turn the fans on when ever the motor gets to a preset temperature. This would be my preferred setup but do not really have any idea where to start and what to use for the sensor. Is there a how to on this forum or somewhere else? Any input greatly appreciated,
Con

 

the Series 3 XJ-6 already has a Thermal Switch-Sensor fitted into the radiator.

it is located at the bottom left corner of the radiator at the engine side, as you stand in fromt of the car,

this thermal switch-sensor is used to start and to stop the small auxiliary cooling fan located at the front of the radiator below the front bumper.

 

Mine were all V12's.

The actual radiator dimension is the same, just different hose spouts.

As Jose said, there is a thermo switch already provided. The V12 have that switch in the water pump Inlet spout/elbow.

I wired all mine as follows:

RH fan is thermo controlled, via a relay, which is Ign activated. Means NO run on after shutdown.
LH fan is A/C controlled, so whenever the A/C Compressor is running, that fan is running. ALL my Jags had an A/C by-pass switch installed (by me), so the system could be used as designed without the Compressor running.

With the above system, I had ZERO heat issues. With the A/C on, so LH fan running, and 45C outside, suburb driving, the Temp gauge never moved, AND, the RH thermo fan NEVER cut on.

Not so hot days, NO A/C Compressor, so no LH fan, same driving, the RH (thermo) fan rarely cut in.

Mandatory requirements:

Radiator is 100% clean inside and out
82C thermostat, of the correct length.
Pressure caps etc all in 100% order.

Without that above being spot on, you are wasting your time.

 

Thanks Jose and Grant, so if I connect the fans to the temp sensor the through the ignition wires and a relay so that both fans operate at the same time they will come on at some factory pre determined temp and turn off when the motor is off? Will the aux fan work as well if left in the circuit? Is it still required? At present the a/c is not working and I haven't got to fixing it yet. The main cause for that is a hole in one of the hoses. I am fitting the Jagaire manual control module when I get to the a/c repair.
Con

 

the factory designed the auxiliary fan to run after the engine is shut off if the temperature is still above the thermal switch sensor preset.

I don't know if adding two more fans to the circuit would overload the factory setup.

Why do you want to add more electronic fans? Why not just replace the plastic fan?

my '84 is still with the original plastic fan and auxiliary fan setup and it never overheats. but if it goes above the preset temp, the auxiliary fan comes on. As small as it is, it is very effective. So the answer to your question is: Yes it is needed. These 4.2 engines run hot.

 

Jose
I noticed that the original fan has several cracks on the hub. I am just exploring the possibility of using e-fans because the replacement plastic fans are so expensive here in oz. Cheaper in the USA but the postage kills it. May never need to replace but.....
Con

 

If that's how you want it to operate, yes. It can be wired that way.

The circuit for the existing elect fan is designed to give key-off after-cooling. If you want to keep that feature, it's doable with your new fans

The existing switch is set to close at 94ºC as I recall

Yes.

Personally I'd ditch the existing aux fan if you're adding two larger fans.

But with or without using the existing aux fan you might want to consider the current draw of the Falcon fans. The alternators used on the Series III XJ6 were not very high output. I think they're only 60-65 amp or so...which is adequate, barely, without adding any extra loads. Grant will probably know how much they draw

Cheers
DD

 

oh I see, you are in Australia.

have you checked eBay Australia?

also you have some excellent used parts suppliers there, a used fan might be an option if it is not damaged.

I am not sure if adding electric fans results in better cooling. You will need to do away with the Shoud which is an important part of the cooling system. You might end up with electric fans that run continuously making for a very noisy setup.
Francis will chime on this since I have no experience with eliminating the plastic fan and adding electric fans.

 

Been reading this thread with interest as I am thinking about going electric in my v8 '79. As to the cracks in the original fan, I would definitely get it out as soon as possible as I understand if they fail at speed they can do a lot of damage and if the bonnet is open it can do damage to you.

I would look into keeping the original fan shroud and getting a "puller" fan that just fits in the circular opening. Then it will look sort of stock and should cool well. There are a lot of articles about the importance of a properly designed shroud being as important as the fan itself. Definitely check the current draw vs the alternator output.

In the USA most hot rods have electric fans (as do most all new cars). Jegs and Summit carry a wide range of options. Of course, I don't know about the aftermarket situation in other parts of the world.

Jeff

 

Following Doug's line.

The Falcon fans I used way back then were the EL Taxi Pack. Made by Bosch Germany. EACH motor had a draw of 8amps running, and my meter was not high enough to read the "start up" amps.

I ditch ALL the V12 stuff, and went with a blank canvas. Main reason, my plastic fan spat a blade and punched a hole in the bonnet.

I upgraded the alternator, had to, and a Bosch 110amp from an XJ40 fitted perfectly.

I used ZERO factory wiring, blank canvas again.

The HE V12 temp switch is 85C, and since that is sensing Bottom Hose Temps, PERFECT, for what I wanted. Other markets may have different temp switches, and I now know the 6cyl temp, THANKS Doug, and that would be too high in MY opinion. Various switches of different temps are all over the place. I even have some in the stash in the shed.

Down under, Tridon has a good spec chart in the back of their catalogue, with spanner size, thread specs, temp settings, etc etc.

BUT

The Falcon fans are NLA via Ford, and the aftermarket are Elcheapo, made "over there" and I will not fit them.

Since I did mine, 99% of cars have Efans, so the selection now is way better than I had. Some even talk of the X300 etc fan pack., but I have not done the measurements.

 

In my experience, either use OEM fans from a good make (eg pull then from a scrapped car) or, if funds allow, use SPAL brand fans and the largest you can get in there. All other fans I have used have failed quite quickly.

 

Thanks for all the info. I have sourced 2 fans from a EF falcon not sure of the make yet but they have a frame set up to mount to a jag. $40 for the pair including the frame. I will check out he current draw when they arrive. I think if they check out ok I will try to find a fitting kit which includes the temperature control so that I don't have to mess with any exg wiring. I have experience with the older wiring, not good.
Con

 

Well done.

When you look at the frame, as you call it, there a 2 lugs poking out, 1 on each side. I cut them off.

Slide that assembly into position, the top "flange" of the frame will sit nice and flat on the steel crossbeam of the actual radiator.

Place something under this beam, and drill 2 small holes through the "frame flange" and the beam. The "something" is to stop the drill bit drilling the radiator cross tube when you break through.

Fasten the fan to the top of the actual radiator.

The bottom securing in the V12 is simple, as I reuse the existing 90deg brackets that once held the fan shroud tin work. You may have similar, or simply bend something up to hold the frame against the radiator.

Jobs done.



This is those fans in my car. The lugs I talked about were cut off to allow the unit to slide past the 2 top radiator hose spigots (the V12 has 2 top hoses). Also, i saw no real way of using them for attachment.

 

I have twin fans from an ED falcon in my S1, they work perfect. The S1 doesn’t have a sensor like the S3 so I have an adjustable sensor with the probe going into the top radiator hose. Set at 85c. Both fans come on together.
I also have them wired up to the air con switch so they come on whenever the air is on, with a diode in line to stop power feeding back to the aircon switch if the fans come on from the sensor when the air is turned off.

 

Hi Clarke, this seems like what I would like to do. A separate controller would stop a lot of messing about. Where did you source your diode?
Con

 

The set up was in the car when I bought it but not working, I just ran through the process of repairing and getting it operational.
A suitable diode should be on the shelf at Jaycar. I tested mine and it was ok so stuck with it.