Please explain this...
 

I am curious as to what he was referring- I am familiar with the hazards of water/mud with electric fans (I was going to wire a kill in the SPAL) but are there other issues to consider with the clutch fan setup?

Cooling system upgrades are high on my list right now - Houston rush hour, 40 miles daily. I am thinking this fan and the Poison Spider hood louvers will be perfect for my Gulf Coast Expo/DD.

As pointed out in the first post of this thread, my long term overall average mpg has been 18.5.

I have filled up twice since the mechanical fan conversion. Both tanks were mostly around town and some 50 - 55 mph non-interstate roads.
The first tank calculated to 0.5 mpg less than average, and the second tank calculated to 0.1 mpg above the average.

The first tank was lower by a comparatively larger amount probably because I spent quite a bit of time monitoring temps sitting still, idling, and otherwise seeing how the fan behaves.

I'll update again after two more tanks. It's looking good so far.

I would rather have a spal fan which is has a sealed motor then a mechanical fan to get hit with mud or water or small rocks

Nothing wrong with wanting something different. That's what sparked this thread.

I like the fact that you have eliminated those 20 degree temperature spikes.That bodes well for fluid longevity.

I'll be keeping an eye on it once I get into the woods on a hot day. The transmission temps can spike to around 200°F or more, even with an aux cooler, when there isn't much forward motion. I'm hoping the mechanical fan will keep the temps well below 150°F. I already know the other under-hood temps are a lot lower.

Remember the "old " flex fans, the higher the rpms, the flatter the arc of the blade? They pulled air at idle,flattened right out at highway speeds, less power robbing drag.Mechanical all the way. . .

Yes, I remember those. I also remember when the fan had no shroud; it was just really close to the radiator on a long spindle from the water pump.

For those not familiar with the thermally controlled viscous fans, there is a bi-metal spring on the front of it which monitors the temperature of the air coming through the radiator. When the air is "cold", the viscous coupler lets the fan slip more than when the air is hotter. What I've seen so far is, when the fan is slipping the most, there is still plenty of air being pulled through the grill.

Subscribed, intresting thread, and write up thanks Ron.
Agreed retro, kinda like that, and it's funny too...some TJ owners remove the OEM mechnical fan and swap in a electrical fan.

I have the Mopar AUX cooler to put in, but I have access to a thermal fusion camera at work that I've been meaning to take some before pictures of the engine bay, tranny lines....I do this and post them up, see how hot a stock bay gets in typical bumpber 2 bumper traffic.

I would love to see some thermal pictures of the MOPAR cooler after the transmission has worked hard with the torque converter unlocked. The lines go into the bottom of it, which is contrary to what the instructions for virtually all other cooler manufacturers recommend.