ronjenx

The weather hit the 90's today, so I did some testing of the mechanical fan conversion on the trail in 4wd.

In 4hi, during most of the slow ups and downs of the trail:
The water temp hovered right around 195°, once in a while hitting 198°.
The transmission temp hovered around 130°, spiking once or twice to 135°.

In 4hi, up a steep ¼ mile climb:
The water temp remained in the mid 190's.
The transmission temp hit 170°, and never went over. That was with a lot of torque converter slippage, because the speed didn't allow it to lock up.

I repeated the runs shown above in 4lo. The water remained in the mid 190's, and the transmission temp remained about 140°.

As we all know, 4lo really lightens the load on the transmission and torque converter. The torque converter even locked up on the lighter stuff.


I was also running the A/C at different times during the test. It operated well, and had no effect on the water temp.

Cats&Jeeps

Thanks Ron for pioneering the setup and providing research data! Will make the same install this weekend!

Best regards

ronjenx

Thanks. I'll be keeping an eye on it all summer. Still need to go through a winter to see how it behaves. You can bet I'll have it on the road when it's 30 below!

rinkishJK

That fan will roar at --30!! Excellent work as usual sir!

mechano

What about when OE fan is removed? This would likely cause a MiL/SES light to appear on the dash considering there would be an open circuit..What r u doing to combat this issue? Or r u using black tape .
I personally think this is a fantastic idea which would be great for city and wheeling situations, only draw back is the Engine light thing.
Cool mod and work man.

ronjenx

No light has appeared so far. I'll check for codes.

edit to add:

No active or pending codes.
Maybe the fan is keeping things below the electric fan request threshold. (A/C fan request included)

CerOf

Great mod! This is now on my list. They say there is a slight hp loss with mechanical, but the cooling capabilities are far more important IMO.

It is why they switched from electric on the WJ to mechanical in '01.

Same reason the ZJ with a 318 has a higher towing rating than the 360. 318 had a mechanical fan with the thermal coupling (often posted about the start up roar) versus the 5.9s electric fans.

I'm a fan (get it?) of mechanical fans.

isolated1523

Is this only for automatics, or will the shroud work with both?

ronjenx

There is another part number for the shroud for manual transmission JKs.
I think it's 68039594AA. Haven't researched the differences.

Looking at mine, it's not obvious what the difference would be.

Of all the benefits that seem to be gained from my experiment, the lowering of automatic transmission temps is the most important one, in my opinion.

DeucesALLin

... this is about the fact that though the SPAL unit fits perfectly, and is sealed, it doesnt offer the same CFM as the OEM unit and is susceptible to the same automatic controls as the OEM unit. That means temp fluctuation- a bad thing in any sealed fluid system.

OP, do you feel this mechanical fan will be more robust under harsh conditions (muds,rocks,water) then an electric unit?