See the update below:

When I did the cam install on my truck, I put in a Flex-A-Lite electric cooling fan as well.  The purpose of this was three-fold.  It frees up a few hp the majority of the time when the fan isn't running, it allows me to shut the fan off for stream crossings so I don't have to worry about trashing my radiator and it means I didn't have to worry about drop brackets for the radiator when I installed my body lift.

The model I used was the Black Magic 15" fan.  It comes mounted in its own shroud with the thermostat built into the housing.  When the shroud is mounted up against the cooling fins, the copper bulb of the thermostat is held up against the fins as well.

Mounting was rather tight.  Not because of the engine being in the way, but because the AC hoses were.  The fan has to mount sideways and clamps to the sides of the radiator.  It won't fit standing upright.

Sorry, I don't have any pictures of this install because I didn't think of taking any before I ripped it all out again.  I had problems with the fan from day one.

First was the thermostat.  It's an adjustable unit from 180º to 240º.  I could never get it to turn on and off when I wanted it to.  If I had it set to come on once the temperature started rising above normal, it would never shut off after it cooled it down.  I even let it run for 30 minutes after shutting the truck off and it still wouldn't shut off.  Just barely turning the adjustment knob would shut it off, but then it wouldn't come on again even when the temp gauge was right near the top of the scale.

Bad as it sounds, I didn't worry about it too much at the time because it was the middle of the summer and I always had the AC on.. There is a relay that turns the fan on whenever the AC clutch is engaged.

The second and real problem was when traveling at slow speed for extended periods with the AC on.   The fan just couldn't cool enough.  The temp would rise and would not come down again.  I first noticed this the first week a couple hours into a desert wheeling trip (about 105º BTW). 

We slowed down to the point where the fan couldn't keep up any more.  Even after getting out and turning the knob so the fan stayed on all the time and running with the AC off, the remainder of the trip was spent right near the max point on the temp gauge and I shut down several times to cool a bit.

After getting back onto a decent road, the temp went down and was OK.

I called Flex-A-Lite and talked to Rob in tech support.  He was rather surprised that I was having a problem with my little 2.6l engine.  The Black Magic was supposed to be enough to handle 5.0l V8s. 

I had checked the rpm of the fan using an optical tach I have for measuring prop speed on model airplanes.  I measured about 1800 rpm.  The fan is supposed to be turning about 2200 rpm.  Rob is a good guy.  I thought I had a problem with the motor (or maybe the wrong one.  They have another almost identical looking fan that turns at 1900 rpm) and he offered to send me a new one to mount in the fan and try out.

Now, about 6 weeks later I finally get the chance to try it.  I took the fan out and replaced the motor.  However, when I tached the fan this time I got the same 1700 - 1800 rpm.  I guess my tach isn't calibrated very well since I've got two motors that turn the same speed, but the problem still exits.   The fan doesn't cool enough for desert use.

Soooo, what this whole page is about is how to mount the fan in your existing shroud.   Basically, I decided that the problem was that the Flex-A-Lite shroud just didn't cover enough of the radiator for the hottest days with AC running.

First thing you'll notice about the fan is that it mounts on two square tubes that run from one side of the shroud to the other.  The ends of these tubes have a threaded insert that each take a 10" threaded rod.  This is how it's adjusted to fit various radiators.  Screw them in or out more for a narrower or wider fit.  What I ended up doing is removing the fan, motor and square mounting tubes from the Flex-A-Lite shroud and mounting it in my stock shroud.

To do it, you'll have to shorten the tubes.   I cut about 2" out of the middle of the long end of the tube.  You can't just cut off the end because they have threaded inserts for the rods.  I cut the end of the tubes off, then another 2", then welded the ends back on.  You could also just cut the ends off and try to remove the inserts from the cut off piece and re-place them into the tubes again.  It looked do-able, but welding was easier for me.   If I remember right, there's two rivets that hold the inserts in.  You'll have to drill those out to remove the inserts then re-rivet after cutting the end off.

Here's a couple of shots of the Flex-A-Lite fan and shroud laying on top of my stock shroud.

And here's a couple shots of the finished product.  I drilled 4 holes in my stock shroud to fit the fan after cutting the brackets down a couple inches.  The amount is not *real* critical.  I took off the minimum.  Because the ends of the square tubes hold threaded rods, you could take off much more and still be able to mount it by screwing the rods out a little more.  The fan is a little small for the shroud opening.   It's 15" and the shroud will fit a 17" fan.  I don't know yet how much that will effect efficiency.  I won't worry about it until (if) I have problems next summer.

The next step was setting up the thermostat.  I cut apart the F-A-L shroud to use its thermostat and wiring terminals, but I think you can buy these as a separate installation kit as well. 

What you see here is the adjustable thermostat mounted to the front wall of the engine bay with the copper tube leading to the sensor bulb resting on the fins of the radiator.  Everything is attached with silicone.  It holds it securely, but I can remove it if I want without too much hassle.  Notice that I cut a notch in the edge of the radiator for the copper tubing to go through.  This is because the shroud rests flush against the edge and I didn't want to damage the tube.

Finally, the control box that used to house the thermostat is siliconed to the shroud.  It still contains the circuit board and a relay and was quicker and easier than making my own little box to hold things together.

Here's a few more pictures of the completed install.

On a final note, I still had problems with the thermostat not working correctly.  After another call to F-A-L, Rob agreed to send me a new thermostat as well.  I installed it and it now works like a charm.  The problem was is that there's supposed to be like a 7° - 15° range between turn on and turn off.  The original thermostat had a range more like 30° or more.  It just wasn't precise enough.  The new one now comes on when the temp gauge raises to just over half-way.  After settling back down to the normal position it'll run for about 30 - 60 more seconds then shut off.

Works good now.  The only thing left to find out is how it works wheeling in the desert next summer with the AC going.

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Update:  After running this fan for a few years, I've recently changed back to the engine driven fan.  I'd been fighting overheating problems since switching to the electric and after trying several things, the engine driven fan was the only thing to cure it.  

This may still work for you though.  Several people are using electrics without problem, but for me here in AZ, it just isn't enough when temps get up above 95º or so and I'm running the A/C.  With the turbo, the problems became even worse.

I've tried:

1. A new, high efficiency 3 row radiator (stock was a single row).
2. Mounting the fan in the stock shroud.
3. Sealing up the gaps so that the fan fit the much larger shroud opening correctly.
4. A different Perma-Cool fan rated at a little bit higher CFM than the Flex-a-Lite.
5. Changed coolant a couple times (perfectly clean always, BTW).
6. "Water Wetter"
7. A new thermostat.

Sealing the gaps in the stock shroud made the biggest difference, but it still wasn't enough.  In the end, I decided to just drop the radiator (I've got a 2" body lift) and put the engine fan back on and the problems have gone away entirely.

Created by: Dan Houlton
This page was last updated a long time ago.
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