Just learned my radiator clutch fan was deleted by previous owner, now what?

[Thundarr the Barbarian]

My son's 2000, TJ, manual, 2.5l, 32" tires on 4.88's, broke down a couple days ago. We picked up a new water pump (+ fan clutch) since the current one is likely the original, and the gasket gave up the ghost. Easy enough fix.

We worked on the jeep a little before heading to grandpa's house for Thanksgiving dinner. And here's the topic we argued and debated during dinner: There was no radiator fan clutch! There's a radiator fan, but no clutch.

The radiator fan was bolted straight onto the water pump through the water pump pully. The serpentine belt powers the water pump and the radiator fan. Meaning, when my engine is running, the fan is spinning. The radiator fan will not accept a clutch fan. The fan looks nothing like OEM fans I've found online. AND, it's not an electric fan. There's nothing electric about this setup (trust me, it's not how you ask the question...the answer will not change. It's not electric). There's no auxiliary radiator fan in there either, the one described above is all it's got. And there's no other hacks to squeeze extra squirrel power out of the four cylinders (no throttle body spacer, no cold air intake, etc.) Which was why I was caught so completely off guard by this radiator fan thing.

So, what in the wild world of sports am I supposed to do with this? Is there a benefit to deleting the fan clutch? Or is this a fool's "upgrade" that I should un-delete ASAP? If I read Chilton's right, all I need is an OEM radiator fan that will accept the fan clutch...then slap in the new water pump and attach it to the fan clutch and radiator fan.

But it's never that easy....or is it?

 

[k1n3k]

I'd undo it personally. Fan clutches on mechanical fans became widespread for a reason. Turning a fan 100% of the time isn't needed, and they take quite a bit of power to turn, a surprising amount. Having a viscous clutch in there is a nice thing to have. As for what parts you need, heck if I know. depends on what they replaced or hacked up to make the non-clutched fan work...

 

[TheBoogieman]

 

[Gilaguy23]

If you been around wrenching for decades you'd remember "Flex fans" . Thin aluminum blades that flatten out at RPM to save power and MPGs yet cool like a winter blizzard at low speeds due to their extreme ability to move air. Almost as convincing of BS as a K&N rock strainer. Id guess it was installed because it was over heating at crawl speeds, and this was the hopeful fix. Id get rid of it and use the OEM style fan and clutch. Problem solved.

 

[Thundarr the Barbarian]

Thank you! That describes the fan perfectly: Thin aluminum blades that are curved along their length...and with no place for a clutch to attach. Sounds like snake oil. I'll ditch it and go back to OEM.

It appears simple enough to buy an OEM fan that mounts to the water pump pully. But all the schematics I've found, except Chilton's, show an additional (electric?) fan that mounts directly to the front of the radiator. That additional fan applies to the 4.0l, but not the 2.5l, correct?

 

[Thundarr the Barbarian]

I'd undo it personally. Fan clutches on mechanical fans became widespread for a reason. Turning a fan 100% of the time isn't needed, and they take quite a bit of power to turn, a surprising amount. Having a viscous clutch in there is a nice thing to have. As for what parts you need, heck if I know. depends on what they replaced or hacked up to make the non-clutched fan work...

Ya, I think we need to go with OEM. Thanks for the info.

 

[k1n3k]

K&N rock strainer

Best description I've heard of a K&N

 

[OldBuzzard]

My son's 2000 ... If I read Chilton's right...

The Factory Service Manuals are here.

2000 TJ Parts List

2000 TJ Service Manual

 

[GoldenGorilla]

If you've seen any tests of fans without clutches, they can draw like 20hp at high rpms. That 2.5L definitely doesn't have 20hp extra lying around to give up!

 

[1n5ane]

You could be losing as much as 30Hp with a fixed fan.

 

[B1Toad]

But all the schematics I've found, except Chilton's, show an additional (electric?) fan that mounts directly to the front of the radiator. That additional fan applies to the 4.0l, but not the 2.5l, correct?

I think the electric fan was a 2.4 thing.

 

[KingCarGuyZ]

I have a 4.0 so take all of this with that grain of salt.

The water pump on the 4.0's has a threaded stud that the mechanical clutch threads on to the fan then bolts to that clutch. It works fine, its not terribly efficient, but its simple and reliable.

If I were you, I would take a look at this thread:
https://wranglertjforum.com/threads...pal-19-850-watt-electric-brushless-fan.78963/

I am currently in the middle of the SPAL conversion - I like how its going. in Oregon you probably have no need for the added idle cooling the SPAL offers - but you can greatly benefit from the reduced drag on the 4cyl. it's not really "adding" horsepower so much as using the power you have more efficiently. you can use This controller to save a few bucks.

That said, theres nothing inherently wrong with your direct to waterpump approach. It works, just is incredibly un-efficent and robs a LOT of power un-necessarily. (20-30HP is not an unreasonable estimate, especially at RPM) and jeeps don't have a lot to go around - especially the 4cyl's

 

[Thundarr the Barbarian]

The Factory Service Manuals are here.

2000 TJ Parts List

2000 TJ Service Manual

Thank you!