Thread: Thermatic electric fan conversion

After new hoses, a coolant flush, my radiator being rodded and the best quality coolant, I have come to the conclusion that all Rover V8's just like to run at inferno. My 3.9 cruises at 96 degrees on the highway, and gets even hotter on hills or when towing. Alisport offer a conversion package but it is nearly $2500.

The first part to get is the actual radiator. There are lots on Ebay, 3 and 4 core versions for varying prices. All advertised for automatic versions that have both an oil and transmission cooler built in. After some emailing, ASI performance agreed to make me one that just had the engine oil cooler. See the attached picture. The item is titled "4 ROW PRO ALLOY RADIATOR FITS FOR LANDROVER DISCOVERY 3.9 RANGEROVER 3.9- 4.2" It cost about $500. As long as it is advertised for your car, and the core length and width are the same, you should be right.Core Size: 690 x 388 x 48mm. Inlet/Outlet:35mm. Most of them seem to be the same product anyway, just with different retailers.
Radiator.JPG

After inspecting my new radiator, I noticed they had messed up the oil lines. The fittings were female instead of male. They ended up reimbursing me for what it cost Pirtek to do up some adapters. The inlets also appeared to have baffles in them. After looking at the original radiator, I decided to drill them out as blowing through them was more restrictive.

Next came the fan selections. Electric fans start on Ebay for $20, right the way up to Davies Craig for about $300. But without a shroud, they are very inefficient. EL Ford Falcon fans match up distance wise perfectly. They are also meant for a 5.7 Litre V8 that will thrashed in the aussie heat = plenty of cooling. The 3.5, 3.9, 4.0 and 4.6 EFI radiators are all the same size as far I'm aware of.
EL_thermo_fan_measurements.jpg

As for where to buy the fans from, I had a choice of a used unit but I decided against it as it was already 20 years old. OEM was going to be $500, so I found a highly rated after market set on the Bay. While some were only $100, this one was $200, and came with a 3 year warranty as opposed to 6 months. See Ford Falcon EL EF Radiator Thermo FAN Twin Connection 1994 1996 Brand NEW | eBay Also see "Ford Falcon EL EF Radiator Thermo Fan Twin Connection 1994-1996 Brand New" Or find a similar set of reasonable quality.

Finally sitting the radiator on top of the fans was reassuring. It perfectly lined up. One of the plastic mounts on the fan shroud had to be removed, along with one other little piece of plastic. I went to clark rubber and got a variety of rubber edging. Running a high temp RTV sealant everywhere to keep all the edgings on is a good idea. The main thing to remember is to make sure that no fan plastic or shroud is touching the radiator. The very soft edgings work a treat sealing the gap between the fans and rad all the way around.
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The radiator has a metal edging/extrusion on the top and bottom side that is about 10mm above the edge of the core, making it a prime place to drill into. Be very careful you do not drill too close to where the core starts. The fans were secured with 4 self tapping screws and washers on the top and bottom. The fan shroud is also equal to the base of the radiator so it supports itself on the chassis. 12784508_1113160962036494_1427294264_n.jpg


The radiator should now bolt straight into the car. Now we have to connect it up. There are many ways to control them, but I believe an Engine Watchdog is the way to go. They are very reliable and measure the true engine temperature from the head, not the coolant or air temperature. I used two sets of wires and relays rated to 30A. One for each fan. The engine watch dog fan relay wire then attaches directly to the negative and positive activation terminals of the relay. Grounding the negative EWD wire, and then grounding the relays separately did not work me for me, so run the EWD relay wires straight to the relays. I grounded the fans straight to the chassis, and ran the positive wires straight to the relays, then to the battery. 12804032_1113151022037488_1270040117_n.jpg

You can decide what temperature you wish the fans to activate at. I chose 85, so the engine heats up quickly and doesn't stay cold. After it hits that usually It drops down to about 78-82. I have also selected the watchdog to turn the fans off at 75 degrees after they have been on. In winter the fans often never turn on. The viscous fan can still fit, but I have removed mine. I would take it on a long camping trip just in case. However after six months the system has performed without fault. The car cruises easier on the highway, and the economy is down between 0.5 - 1 L/100. before the fans come on and there is no fan drag even on the alternator, the car feels like it flies. There is no slow constipated land rover warm up in the morning, it just goes.

just a quick q. regarding your trigger switch. if you were going for setting your fan up permanantly for a temp trigger why did you go with an adjustable switch setup? currently looking at slightly cheaper or more robust (more waterproof) options as a lot of the kits on ebay are over priced for what they are.

instead of an adjustable switch would it be easier just to use a temp probe switch? trident have all sorts of probes that switch at various temps. and am thinking of setting the cooling system up to open the thermo at about 77 degrees, fans cut in at 85 and off at 80. which would roughly be running at 10 degrees below OEM after warm up. where i see it makes the most power for me. i run LPG/petrol. mainly LPG.

i know lower temps usually mean faster wear on engines but it feels like it runs better just below where the temp settles. also want to swap it later down the track. but for now i want some more fun out of it.

Thermostat | Tridon

ALL tt2000 thermostats fit. OEM replacement is the tt2k-190. im going to use the 2k-170.

Saas Genuine Water Temp Sender Adapter Silver 32mm NEW | eBay
it may not be the right size but ill find one with the correct size to fit the top hose of the 4WD.

from there, split the wire, 2 relays, 40 - 50 amp fused power to the fans and back to earth. cheap. if splitting the wire stops activation ill just use a first stage relay that supplies more juice to the other 2. seal the box with silicone, seal the connections, have fun?


is this more or less the way to go?

the other way to go i think is this way. still researching but limits your temprature selections as they only really made 3 usable ones in the range we would want (who on planet earth thought it would be a good idea to make a switch that kicks in at over 115 degrees!?)

tridon TFS 100 (90 close 80 open) 170 (92 close 87 open)/171(87 close 77 open). can directly replace TFS145 (102 close 97 open)which is the switch that (my assumption is) powers the air con thermo fan on the front of the car. but obviously you send the wires to your electric relay setup instead of the tiny little pansy fan that looks more like a hood ornament than an actual usable engine componant. just remember to make a bypass to allow at least 1 of the fans to run while your A/C is working. or if your gonna run low/high fan setups use the low side to power the A/c and high side direct temp switched.