Does anyone know a good reason why Chrysler decided to use both a mechanical and electric cooling fan setup on the 4.0 XJ? The 4cyl XJ and both the Wranglers and Grand Cherokees of the same era use a mechanical fan only.

 

I could be wrong but I think the WJ only has an electric fan.

 

And I ran my 98 XJ for over a year without the mechanical fan. Never overheated. I did finally add a mechanical fan but still no shroud and still no overheating. I always think it’s odd when people on here try to blame overheating on the missing shroud or bad fan clutch. My jeep also has over 217 thousand miles and it had 215 when I was running without the fan. And it’s been through hell and back. Maybe I’m a minority in that sense.

 

I don't have any overheating issues and I am not blaming the factory fan setup for causing overheating issues, I was just curious as to why Chrysler decided to do it that way. However I do find it hard to believe that you ran without the clutch fan and only the factory electric fan and didn't have any overheating problems.

 

I wasn’t saying that. Just saying I don’t believe it’s as necessary as some believe. And the only time it would get warm enough to kick on the e fan was if I let it idle too long on a hot day. Also my ac does not work so the compressor never ran. When the e fan did come on it would cool it down below 210 and shut off and just keep cycling that way.

When I got the jeep it had one of those aftermarket electric fans that have plastic pegs that go through the radiator fins hooked up to a switch. I drove it 25 miles home after buying it and during that drive it rubbed a hole through the radiator.

So I pulled the radiator from a 99 I had sitting in my garage for a couple years and flushed everything well first. Installed a new thermostat, temp sensor, hoses, water pump and thermostat housing. I couldn’t for the life of me get the mechanical fan off the 99 to use on the 98. Then a year later I picked up another 98 that was totaled. I was able to get that fan off so I used it. The shroud was busted though so I’m still running without it. Now that I have the mech fan it runs very cool. Takes a while to hit 210. Normally hovers a little below. The e fan has not come on once since either.

 

A relatively small radiator for the engine size and type? Mechanical fans will move more volume than an electric of similar size. Proven reliable design? Cheeky and delightful? Would have been more of a bother to put in 2 mechanical fans. General Chrysler shenanigans. Don't quote me on any of this.

 

I guess a better question would be what is the reason for the electric fan rather than one large mechanical fan like the Wrangler and ZJ?

 

in hot climates it makes a huge difference. I had no electric fan for a while on my jeep and idling in traffic, drive thrus and general slow creeping and offroading the temps will go up and beyond without it. I finally fixed mine and what a huge difference it makes. temps still get to 220 but they stay there unlike no fan and itll keep creeping up. Thank god for ac and the fan now lol i was dying in 100 degree temps basically

 

I replaced the complete cooling system on my '96 back in 11/2016 eliminating the hcv. Otherwise it's completely stock except for the hd clutch fan which I don't believe is necessary. I'd say the system is operating at peak efficiency. As per the design the auxiliary fan comes on when the a/c compressor kicks on. It has yet to come on otherwise. The mechanical fan does the cooling just fine even with the auxiliary trans cooler in front of it. I can do extended idles with the a/c on in the hottest weather and not climb above 210.

My guess as to why whoever designed the cooling system with the two fans is because it works and provides better fuel mileage than one large mechanical fan would.

 

I would guess it’s either a smaller radiator or something relating to the reasons why the alternator and ac compressors are in different locations also. Maybe just because the engine bay is smaller? And also wouldn’t it have been AMC not Chrysler who did it? Did the first 4.0 cherokees have both as well?

 

I suspect its a question of generalization and assumptive prevention from an engineering viewpoint.

Our XJ's were designed and expected to perform as workers.. load carriers.. whether you fill it with several hundred pounds of visiting family members... or a load of bricks for the garden. And many of us either have the factory tow package, or have added a tow hitch to tow small trailers/boats/rental equipment. All that extra weight causes lugging. Which cause heat build-up.

Soo... the engineers felt it would be wise to use both the mechanical and the electrical fan on the XJ to keep it running cool.

At least.. that's how I see it.

 

Electric fan only is standard on the WJ. With factory tow package the WJ comes with a mechanical fan as well.

 

The radiator is wide. Need 2 side by side fans.

And, AMC invented the XJ. Not Chrysler.

 

AMC did indeed create the XJ. They also pretty much had completely designed the ZJ as well. AMC had intended it to replace the XJ and be the new Cherokee. Then when Chrysler acquired AMC they decided to sell the ZJ as the Grand because the XJ was still a big seller. The ZJ pretty much started the "luxury" SUV market.

 

And you know who had huge influence in the XJ design and uni-frame construction?

Renault.