i have a 88 f-250 7.3L my clutch fan sounds like a jet taking off all the time would it be wise to remove the fan and clutch and replace it with a electric fan? and is it good for the engine to run cooler or warmer. which would get the better fuel mpg..thanks

 

The fan running all the time is sucking up fuel to the tune of several MPG.
I have tried the electric fan route, it was not a sucsessful experiment though.
I removed the fan and fan clutch, put the bolts back in to hold the water pump pulley.
I got two 18" auxiliary fans which I installed where the regular fan was located behind the radiator.

Plus facts:
Power was increased
MPG went up about 1.5 MPG over what it was getting with the fan clutch working correctly
the engine was much quieter
warm up time was reduced in the colder months

Operating facts:
The fan was not required at speeds over 20 MPH
The fan was required at speeds over 65 MPH

Minus facts:
My son turned the AC on while the truck was not moving and did not turn the fan on, the AC high pressue fuse blew and I lost my very expensive R 12 freon charge.
The fans did not last very long, and at 80 dollars each they got to be expensive, more so than the fuel saved.
Under high load slow speed conditions the two electric fans were not really enough CFM to keep the engine cool enough.
During the winter while plowing snow (high load on the engine at very low speed and RPM), the extra amperage draw from the fans plus running my lights, heater and snow plow were more than my 130 amp alternator could keep up with.

NAPA had an electric fan they could order for me that was large enough as far as CFM's went, but the cost was over 300 dollars each. And the amperage draw was still large. I could not justify a close to 400 dollar experiment with the luck I had had with the other fans.
Also there needs to be a relay the turns the fan on when the AC compressor clutch enegizes, that is not a big deal but it needs to be there. Also there should be a thermostat to control the fans automatically, I had mine under full manual control.

In answer to your question about warmer or cooler, warmer is better for more complete combustion of your fuel.

With the current price of fuel I may consider the electric option again, but I will have to bite the bullet and go for the good fan (expensive) if I try it. I may also have to upgrade my alternator again to be able to run everything in the winter.
During my time as an OTR truck driver, we had air clutches on the fans on our big rigs.
Flip a switch and turn the stock very large fan from Manual ON, Automatic ON OFF or Manual OFF. This was a great thing, but with the fan located on the water pump on our trucks I have not figured out how to do it yet. I am sure there are parts that could be assembled to relocate the fan off the water pump and drive it with an extra belt through an AC clutch so you could turn it on and off.

That just about concludes my observations on electric fans in place of the stock fan.