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Writeup: Replacing the Mechanical Fan w. another OEM Aux Fan

maalox said:
Sorry to bring back an old thread, but after reading through a bunch of fan upgrade posts, this one seems to offer the most collective knowledge. I've all but decided on an aftermarket fan(or fans) to replace the mechanical OEM unit, as the Taurus fan, while inexpensive, requires modifications that I don't want to get into. My thoughts on wiring the fan were as follows:

Wire the new fan to run on low speed with keyed 12V. The mechanical fan runs constantly, so I can't see any inherent over-cooling problem(as if you could get an XJ to run that cold, ha!) with running it all the time. Has anyone wired the high speed to come on with the OEM Aux. electric fan? I was thinking a relayed circuit using the power signal going to the OEM fan to turn the main electric fan to high. Thoughts?
Click to expand...

The mechanical fan may "spin" all the time, but if the clutch is reading the temps as it's supposed to, there is little or no load on the engine turning the mech. fan when it's cold. I tried to simulate the mechanical fan operation with my replacement electric fan by using a variable speed controller to do the same thing. It only comes on when the temp gauge hits 195*(LO speed) and kicks on HI when the temp hits 210*. Hardly runs at all in the winter. Running it all the time is not a good idea as it wears out the fan quicker and puts unnecessary load on the electrics. And I have my stock aux fan wired separate from the new replacement electric fan as the aux fan doesn't come on until 218*-220*; too high IMHO.
 
Just as another note here...

Depending on how you mount the additional OEM aux fan, the older style straight blade fans have more clearance against the pulley than the newer 10 "S" blade fans.

The "hub" that sticks out in the middle of the pulley (don't know what you would call it) is the main thing that would cause issues running two newer style S blade fans as the fans are the same distance out as the center section. Hard to describe but if you take both styles side by side and compare you'll see what I mean.
 
comanche91 said:
The mechanical fan may "spin" all the time, but if the clutch is reading the temps as it's supposed to, there is little or no load on the engine turning the mech. fan when it's cold. I tried to simulate the mechanical fan operation with my replacement electric fan by using a variable speed controller to do the same thing. It only comes on when the temp gauge hits 195*(LO speed) and kicks on HI when the temp hits 210*. Hardly runs at all in the winter. Running it all the time is not a good idea as it wears out the fan quicker and puts unnecessary load on the electrics. And I have my stock aux fan wired separate from the new replacement electric fan as the aux fan doesn't come on until 218*-220*; too high IMHO.
Click to expand...

How does the variable speed controller measure temperature? Does it require adding an additional coolant temp sensor? I'm trying to keep the install as simple, using as few extra components as possible.
 
maalox said:
How does the variable speed controller measure temperature? Does it require adding an additional coolant temp sensor? I'm trying to keep the install as simple, using as few extra components as possible.
Click to expand...

It uses an existing temp sensor (not switch), either the one in the thermostat head for the ECU, of the one on the back left side of the head for the temp gauge. I used the one on the head; it provided a more stable accurate signal to the controller in my case.
 
MoparManiac said:
Just as another note here...

Depending on how you mount the additional OEM aux fan, the older style straight blade fans have more clearance against the pulley than the newer 10"S" blade fans.

The "hub" that sticks out in the middle of the pulley (don't know what you would call it) is the main thing that would cause issues running two newer style S blade fans as the fans are the same distance out as the center section. Hard to describe but if you take both styles side by side and compare you'll see what I mean.
Click to expand...

I used two 97+ 10-blade fans. I mounted the new one as close the the existing aux fan as possible, and actually got more pulley clearance with the 10-blade fan, almost 3/4".
 
My original aux fan bit the dust a few weeks ago and yesterday I replaced it with a 10-blade($16@JY). The 10-blade had a cracked support(only salvageable 10-blade--the latest batch of XJs were banged up pretty good), so I used a dremel to mod the bad fan's support so that the 10-blade could fit.
 
maalox said:
How does the variable speed controller measure temperature? Does it require adding an additional coolant temp sensor? I'm trying to keep the install as simple, using as few extra components as possible.
Click to expand...

The Flexalite model I chose uses a radiator probe- simpler on paper, but a PITA in reality. A shot of copper RTV finally got me good and consistent readings, but initially the probe wasn't making good contact- I've got some corrosion issues, and a new radiator is in my future. Another model uses a thread-in sensor (like Comanche's SPAL, installed in the head, or my XJ's stock location in the T stat housing.) I wasn't sure I had another port of the right size, so I went the "easier" route, which required more fiddling until I realized what was happening.

Something to consider for anyone looking at this mod.
 
I have a 95 with all new cooling system components (everything). It would run just over 210 on warm days sitting at traffic lights. I could also feel the clutch fan dragging the engine when fully engaged. I have a 10 aux fan that works flawlessly. I picked up a 12 blade fan and mounted it next to the aux fan. I used a flex a lite controller and it worked just fine.

My rig overheated horrendously with those two fans. I had to run the heater on high just to go down the freeway and both fans were running full speed. I took the electric fan off and replaced with the stock shroud and clutch fan and all is normal. I REALLY want to get rid of that clutch fan but it doesnt look like its going to happen.

I cant do the Taurus fan because my winch is below my radiator.
 
zluster said:
Actually you will also find some 1996s with the newer style fan, which means its slightly more likely you'll find one at a junkyard.
Click to expand...

Mine has this as aux fan. Fan clutch is bad on mine. :repair:

I was thinking of going to flex a lite, but since the old style fan + new are working for you, I ought to just do that (2x new style fans). Much less pricey.
 
Another plus for the factory style fan- easier mounting. Was under the hood the other day, noticed my rad is leaking again. I'm using the zip mounts currently, but I'd hate to screw up the fins on a brand new CSF. I think I can make some straps to mount it solidly (won't know until I've got it all together), but it would be simpler had I been able to find two OEM fans (notch the bottom mounting tab a little bit, screw the top in place). Just my $.02 worth of hindsight.
 
Does anyone know how many amps the stock e fan pulls (2001 e fan). When I install two stock e fans (2001 e fans), will I have to upgrade my alternator for the rare (or frequent ?) times both fans are running at 100% capacity?

Does anyone have a cfm rating on the 2001 e fans?

The e fans from 97-01 are all the same, right?

Earlier in this thread I know someone stated the motor from another manufacturer is the same as the 97+ e fans and the other manufacturers fan are rated at about 1400cfm. Can any else confirm this cfm rating? How sure is the person who posted this statement about the cfm rating?

Has anyone had any problems running two 97+ e fans?


2001 xj
 
I'm running w/ a 96 and a 97+ fan. The original 96 e-fan wore out, so I did have to spend another $17 at the JY for the 97+, and I was running a pcm that didn't kick the compressor or fan on, so no control of stock e-fan(kicked on when it hit 230* and constant if you unplug cts). I like the belt setup w/ the mech fan pulley delete--there is enough wrap on the alternator for those that were wondering. I'm still tempted to remove a/c components and relocate the alt. and go with an even shorter belt.
 
I wonder how the spal controller would handle pushing two fans from the single PWM. It's rated for 30 amp and the stockers pull 14-17 amp according to another post, so that is 28-34 amp draw. Reason I am wondering is that I'd like to do the 3x10" fans, with two of them being driven by PWM and the third being driven by the ECU. If that did not work then I would do the dual electric setup like Comanche's.

Also, my '85 Cadillac has a PWM controller that drives dual electrics, with both fans running the same (when the A/C goes on both fans go to full). If it works there it ought to work the same here.
 
akxj01 said:
Does anyone know how many amps the stock e fan pulls (2001 e fan). When I install two stock e fans (2001 e fans), will I have to upgrade my alternator for the rare (or frequent ?) times both fans are running at 100% capacity?

Does anyone have a cfm rating on the 2001 e fans?

The e fans from 97-01 are all the same, right?

Earlier in this thread I know someone stated the motor from another manufacturer is the same as the 97+ e fans and the other manufacturers fan are rated at about 1400cfm. Can any else confirm this cfm rating? How sure is the person who posted this statement about the cfm rating?

Has anyone had any problems running two 97+ e fans?


2001 xj
Click to expand...

No need to upgrade your alternator to run two stock fans at all. They pull around to 2000 cfm from the tests I have done.
 
akxj01 said:
Does anyone know how many amps the stock e fan pulls (2001 e fan). When I install two stock e fans (2001 e fans), will I have to upgrade my alternator for the rare (or frequent ?) times both fans are running at 100% capacity?

Does anyone have a cfm rating on the 2001 e fans?

The e fans from 97-01 are all the same, right?

Earlier in this thread I know someone stated the motor from another manufacturer is the same as the 97+ e fans and the other manufacturers fan are rated at about 1400cfm. Can any else confirm this cfm rating? How sure is the person who posted this statement about the cfm rating?

Has anyone had any problems running two 97+ e fans?


2001 xj
Click to expand...


Sorry about asking some of these questions, as some were answered in previous posts, and somehow I missed them. :doh:
 
Over the weekend I installed the Flex-a-lite #110 fan on my 01 Cherokee. I works great. It's a bit quieter now since it doesn't run at all for the first few minutes until engine temp is up. I even installed 2 12v LEDs in my dash to let me know when either one is running since I can't hear them running unless I'm at a drive thru with the windows down. The only problem I am having with the fan is the little temp probe not getting a real good signal. It runs fine when I am at speed but once I stop it's the backup fan that's running for a bit until the new one runs.
 
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