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lose the mechanical fan! free up power!


NAXJA Forum User
:viking: One of the first modifcations that I performed on my XJ was to remove the mechanical fan. While there are many reasons to fear losing the "hard link" cooling fan, the benefits outweigh the fear. Many are conserned that the mechanical fan is the "lifeline" to keeping the engine cool in the event of an electrical failure. BUT electric fans are a fact on most new vehicles and as anyone who has removed a mechanical fan from their engine will attest, the power gains from its absence are noticable and significant especially on a stock engine.
My thermostatic clutch and fan were working properly when I performed the modification. When I was done, there was an immediate (feel at the pedal) power increase, smoother and peppier engine, with shorter fan run times (at full A/C or otherwise). I have since beat the thing offroad with no mercy and subjected the front end to multiple water submersions with nary a whisper of a complaint from the set-up. Given the XJ's reputation to have a "borderline" cooling system capacity (to the engine's heat generation), it seems like a good move.

Remove the stock fan and thermostatic clutch. Use the fan nuts with lock washers to secure the pulley to the hub to maintain the belt routing. remove the stock shroud from the radiator core.
I fabbed upper and lower mounting brackets and mounted a 14" flex-a-lite (pancake motor fan) in the location where the mechanical fan was. Upper mount is (2) fabbed mounting tabs welded to the radiator support. Lower mount is a "Z" bracket bolted to the radiator support and providing a close-off where the fan overhangs the radiator core. The new fan is wired into the left fan's wiring with "T" connectors and waterproofing. The circuit has enough juice to power both fans. Wiring is secured in position with tie wraps. FINAL RESULT looks OE!

Planning and metal fabrication are required so difficulty in that respect is 4 out of 5. Clearance is tight and an improperly secured fan will make contact with the spinning pulleys on the motor.
allterrain said:
I fabbed upper and lower mounting brackets and mounted a 14" flex-a-lite (pancake motor fan) in the location where the mechanical fan was.

Which model flex-a-lite did you use?
Gaius said:
So you are tapping this into the AC fan? The AC fan only cylces with the AC on, doesn't it?
It kicks on when you turn on the AC and also kicks on at like 220 degrees without AC. At least on my 98. I bet there is a way to get it to kick on at a lower temp with a resistor.
You can get a lower temp switch.

Now for the disenting opinion. Given a good fan clutch you gain very, very little by moving to an electric fan. When the electric fan is on, you are using power. Where does that power come from? Going down the highway the fan clutch is pretty much in free wheel mode due to the cold air coming in. If it is spinning, it is because there is heat and the cooling is needed. Is it more efficient to run the fan mechanically or to turn an alternator, store the energy in the battery, then convert it back to mechanical energy using an electric motor?
Agreed, but the disadvantage of a mechanical fan is that it is directly connected to the engine. It's sized to pull plenty of air at low rpm, so at high rpm it pulls too much. The electric operates independently and with much more precise triggering than the thermal clutch of the mechanical fan. It is a trade off, but electric fans will result in more power and economy in most cases.

Plus, I don't like the sound of my mechanical fan. I've only had my xj for a week now, but I plan to pull the mechanical fan. I ran electric-only in a 350 s10 with no overheating probs. Better cooling at idle, and less high-rpm power loss.
If you read about this in other threads on the subject, you'll find that more than a few have tried an electric fan and went back to the clutch fan because the electric wouldn't pull enough to keep the engine cool under a load. One of the problems with an electric fan on an XJ is that our radiator is very short, so you can't fit a very large electric fan.

Hey, if you want to run an electric fan, go for it. However, please be advised that it is not a cure all, and has been known not to work in enough cases that it deserves careful analysis.