2002 Grand Cherokee engine fan won't turn off

[dlundblad]

I added a mechanical fan to my Jeep. Contrary to popular believe on Jeep forums, it DOES rob your engine of a lot of horsepower.. even if you have a clutch good enough to allow you to stop the blade with some rolled up newspaper.

It doesn't help that I have the 4.SLOW turning 31's with tall gears, but I don't like my Jeep downshifting at 65 MPH to make it over a small incline either. This along with the AC running really turns it into a turd.

But hey I now have a NOS Mopar fan made in 2002 hanging on the garage wall now.

*Not saying adding a mechanical fan to a larger engine is a bad idea.. just suggesting not to try it out for this situation.

 

[SteveSRT8]

^^^Totally agreed. When HP is in small supply, you need more, not less.

I have converted many a hot rod from a mechanical fan to an electric one and there are some platforms that REALLY wake up...

 

[IndyIan]

Hmmm, some guys have converted to a elect fan on the 2.0L Trackers, but didn't find it was worth the bother in terms of fuel economy, about 3%, and that's with 127hp and running 3000rpm at 65mph. It has a thermo clutch which has to be much better than the old unclutched flattening fans, but I do find it spins enough over cool in cold temps if you are parked for a while so it does use some hp

 

[SHOZ]

There are adjustable electric fan controllers that are pretty simple. You insert the temp sensor probe into the upper radiator hose. Then use the switched circuit to power the fan relay. In my case the relays are hot all the time and grounding the coil controls the relay.

Here's my set up. It's a Derale D16769, about $30.00

 

[SwampSurvivor]

Originally Posted By: dlundblad
I added a mechanical fan to my Jeep. Contrary to popular believe on Jeep forums, it DOES rob your engine of a lot of horsepower.. even if you have a clutch good enough to allow you to stop the blade with some rolled up newspaper.

It doesn't help that I have the 4.SLOW turning 31's with tall gears, but I don't like my Jeep downshifting at 65 MPH to make it over a small incline either. This along with the AC running really turns it into a turd.

But hey I now have a NOS Mopar fan made in 2002 hanging on the garage wall now.

*Not saying adding a mechanical fan to a larger engine is a bad idea.. just suggesting not to try it out for this situation.

I went from the stock XJ fan to a ZJ fan clutch. The ZJ has a much bigger fan and my fan was not big enough to cause it to slip; the fan was always spinning full bore. You could hear me coming for miles!

It also ate 3-4MPG having that going all the time. Winter fuel mileage was horrible because, even with a good thermostat, it would always run at 180. The 4.0 NEEDS to run above 200.

This spring, I switched to a fan for a 4.0 Cherokee. No overheating and it helped a lot with fuel econ and power. When it gets hot, it does move some air. Most of the time it's relatively silent and doesn't do much.

I like electric fans for most situations. But for what you can fit in the engine bay of a Cherokee, the mechanical fans will always move more air. Everyone I know that has had the electric fan conversions has had nothing but problems. They work fine if you stay on the highway, but the aftermarket conversions just don't hold up off road.

 

[wsar10]

Originally Posted By: dlundblad
I added a mechanical fan to my Jeep. Contrary to popular believe on Jeep forums, it DOES rob your engine of a lot of horsepower.. even if you have a clutch good enough to allow you to stop the blade with some rolled up newspaper.

It doesn't help that I have the 4.SLOW turning 31's with tall gears, but I don't like my Jeep downshifting at 65 MPH to make it over a small incline either. This along with the AC running really turns it into a turd.

But hey I now have a NOS Mopar fan made in 2002 hanging on the garage wall now.

*Not saying adding a mechanical fan to a larger engine is a bad idea.. just suggesting not to try it out for this situation.

I've been over at jeepforum for well over a decade and never saw anybody advocating a mechanical fan being beneficial (in terms of emissions efficiency), the exact opposite is true as the tuarus E-fan is a popular conversion. All that being said I don't visit there as much anymore since it has turned into a much much less mature crowd with kids that wont listen to sense anyway.....

And to reiterate a point regarding your prev. post, a WJ E-fan has NOTHING to do with speed or engine speed.

 

[mister_two]

Had a problem like this many years ago with my MR2, fan won't shut off even after taking the keys out. It was the relay. I had the shop manual which listed specific steps to test the various pins on the relay for ohms, I believe. Bought a replacement relay at Pep boys, tested the new relay at the store which prove to be fine.

 

[SteveSRT8]

Originally Posted By: wsar10
...the exact opposite is true as the tuarus E-fan is a popular conversion.


That fan will blow you out of the way with airflow. There are many others available with similar cfm, you just need the amps to run it...

 

[SwampSurvivor]

Originally Posted By: SteveSRT8
Originally Posted By: wsar10
...the exact opposite is true as the tuarus E-fan is a popular conversion.


That fan will blow you out of the way with airflow. There are many others available with similar cfm, you just need the amps to run it...


I've considered that on mine but I like the simplicity of the fan clutch and stock E-Fan setup.

Plus I only have a 14 year old 130A alternator. That's ... not going to end well. Especially if I throw a winch on

 

[wsar10]

Originally Posted By: Miller88
Originally Posted By: SteveSRT8
Originally Posted By: wsar10
...the exact opposite is true as the tuarus E-fan is a popular conversion.


That fan will blow you out of the way with airflow. There are many others available with similar cfm, you just need the amps to run it...


I've considered that on mine but I like the simplicity of the fan clutch and stock E-Fan setup.

Plus I only have a 14 year old 130A alternator. That's ... not going to end well. Especially if I throw a winch on


I have done the E-fan swap on 2 ZJ's, 1 was a tuarus fan the other was a universal fan from jeg's. I think most guys use the tuarus E-fan because it fits with no mod and they are a dime a dozen at a JY.

 

[dlundblad]

Originally Posted By: wsar10
Originally Posted By: dlundblad
I added a mechanical fan to my Jeep. Contrary to popular believe on Jeep forums, it DOES rob your engine of a lot of horsepower.. even if you have a clutch good enough to allow you to stop the blade with some rolled up newspaper.

It doesn't help that I have the 4.SLOW turning 31's with tall gears, but I don't like my Jeep downshifting at 65 MPH to make it over a small incline either. This along with the AC running really turns it into a turd.

But hey I now have a NOS Mopar fan made in 2002 hanging on the garage wall now.

*Not saying adding a mechanical fan to a larger engine is a bad idea.. just suggesting not to try it out for this situation.

I've been over at jeepforum for well over a decade and never saw anybody advocating a mechanical fan being beneficial (in terms of emissions efficiency), the exact opposite is true as the tuarus E-fan is a popular conversion. All that being said I don't visit there as much anymore since it has turned into a much much less mature crowd with kids that wont listen to sense anyway.....

And to reiterate a point regarding your prev. post, a WJ E-fan has NOTHING to do with speed or engine speed.


Didn't mean speed in a sense of engine speed.. just vehicle speed. At least from what I have seen, the e fan seems to run more in slow, standstill traffic. If its out on the highway, the radiator is getting plenty of air flow to where to fan doesn't have to engage. Hotter days with the AC on might make everything a bit different though..

 

[SHOZ]

On the 1997 Taurus I had the lo and hi speed fans were controlled by the PCM. For engine cooling the fans would not come on at over 35 mph unless the temperature got over 230F or so.

On My Hyundais only the lo speed fan is used for engine cooling. The hi speed is for the AC. The lo speed will shut off at over 30 mph.

 

[tnt31]

Originally Posted By: Nick1994
Originally Posted By: abycat
I wonder if its the fan relay.

+1 that's what I was thinking


That was what caused same issue on my 2000 Durango. When I touched the relay while the fan was running it was very hot. Replaced it and no problems since.