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

[comanche91]

2 Questions for ya...

1 Could you not simply the wiring and just wire up both fans to come on together IE youd use even less fan power as they are both working together and the spal can control them both at the same time???

2 How did you plan to draw air through the 5 inches of radiator not covered by the fan shroud of the primary fan, In AZ we need every amount of cooling we can find to help keep the jeeps cool in 118* weather especially in stop and go traffic??

Otherwise looking to try this on my rig but would want to use both fans at lower speed to help keep things cool...
themud

Good questions. Answers:
1. Yes. You could simply parallel the ECU output turn-on ground signal to trigger a relay to the new fan so both fans would come on at once. Many have done it this way and you would not need a separate controller like the Spal if you did this. But the existing stat sensor for the aux fan turns on too late for me, like 217* or so depending on how calcified the tip of the sensor is. Too unreliable I figured. I also wanted redundancy since both fans would be dependant on the same sensor - not good if the sensor should fail. So I elected to use a separate sensor for the new fan and make it stand-alone w. the Spal sensor that also gave me programmable LO and HI speed outputs and leave the existing fan as-is, but did wire in a manual dash switch if the Spal controller should fail. The Spal can control an additional fan, but only in the "switch" mode, either OFF or ON, but not two fans with both having variable speeds and programmable temps. I'm not using this function.

2. Yes, you are right. The 5" of rad not covered was a compromise. I did this to provide adequate clearance for the 3-1/2' depth OEM XJ aux fan. IF I had cut off the mech. fan pulley shaft housing as on Gojeeps site, I could have fit a 15" or 16" larger fan covering more of the rad surface, because cutting is the only way to provide clearance for the larger fans, but I wanted to be able to return to the mech fan configurtion if necessary. The XJ/MJ rad is only 14" high, so above and below air would have been wasted anyhow. The Jeep XJ aux fans, especially with the later 97+ curved blade models, have an excellent CFM for their size. We get high temps too here in 'Bama, and so far so good, it's performing better than w. the mech fan.

 

[gradon]

I went with the dual electric setup on my stroker last week. My brother cut the old mech fan shroud tabs and rewelded them so that the 2nd fan fits in there like factory(there is 5" in the middle of unfanned radiator). I used a puller to remove the old 4-bolt mount and then I pounded out the shaft. Grinded the alternator bracket and some metal on the right side of the pointer(?)thingy that is by the 0* mark for belt clearance. Used a 2045mmK6 belt and the $18 adjustable temp switch(Advanced). Next time I go to the JY, I'll snag some factory switches and the housing that goes in the dash on the right side of the steering wheel so I can manually control the 2nd fan. I've only put 100 miles on the stroker, so it's still running warmer than a broken in engine(luckily it's not July/August yet). The link on the Jeepstroker's site: http://www.jeepstrokers.com/forum/viewtopic.php?f=8&t=147&st=0&sk=t&sd=a&start=30

 

[comanche91]

I went with the dual electric setup on my stroker last week. My brother cut the old mech fan shroud tabs and rewelded them so that the 2nd fan fits in there like factory(there is 5" in the middle of unfanned radiator). I used a puller to remove the old 4-bolt mount and then I pounded out the shaft. Grinded the alternator bracket and some metal on the right side of the pointer(?)thingy that is by the 0* mark for belt clearance. Used a 2045mmK6 belt and the $18 adjustable temp switch(Advanced). Next time I go to the JY, I'll snag some factory switches and the housing that goes in the dash on the right side of the steering wheel so I can manually control the 2nd fan. I've only put 100 miles on the stroker, so it's still running warmer than a broken in engine(luckily it's not July/August yet). The link on the Jeepstroker's site: http://www.jeepstrokers.com/forum/viewtopic.php?f=8&t=147&st=0&sk=t&sd=a&start=30

Nice writeup in the strokers forum Gradon. I didn't want to cut the fan pulley out so I could return to the mech fan if necessary, but don't think I'll be doing it anytime soon. Noticed you used two of the 1996-type 8 curved blade fans. I'll soon be swapping my square blade fan out for one of those or the 97+ 10 blade fan. Too bad we couldn't stretch those fans to cover the whole rad, but no way. :dunno:

I put in a crate Hesco 4.6 stroker about three years ago in my MJ, and it ran hot (210-225) for 500 miles or so too. I've used both the GDI 3-core rad and a single core aluminum from Bryan at

http://www.alumrad.com/dblpass.html

I much prefer the aluminum radiator.

 

[gradon]

Does the aluminum radiator have an aluminum neck, or is that still plastic?
The pic of the standard cherokee one isn't clear.

 

[comanche91]

The filler neck is plastic, but that's the only thing that is AFAIK. They cost about $200 shipped.

 

[comanche91]

Got some P/Ns?

What part numbers are you looking for mate?

 

[hubs97xj]

That was directed toward Chris, actually. A precursory search returns enough fans, relays, and temp sensors, in addition to wiring harnesses and kits, that were anyone to try that who doesn't already know exactly how to do it, they might as well just buy some random parts. Or maybe I'm just extraordinarily stupid. Could be either. Regardless, I like the idea of being able to just put together a perfect cheap upgrade, and give him some props, as opposed to getting the wrong stuff and burning something important up. That's just me though. I really like part numbers when doing any sort of mechanical or electrical work.

Oh, and I see you over on JU trying to corner the market on 97+ fans.

 

[comanche91]

That was directed toward Chris, actually. A precursory search returns enough fans, relays, and temp sensors, in addition to wiring harnesses and kits, that were anyone to try that who doesn't already know exactly how to do it, they might as well just buy some random parts. Or maybe I'm just extraordinarily stupid. Could be either. Regardless, I like the idea of being able to just put together a perfect cheap upgrade, and give him some props, as opposed to getting the wrong stuff and burning something important up. That's just me though. I really like part numbers when doing any sort of mechanical or electrical work.

Oh, and I see you over on JU trying to corner the market on 97+ fans.

LOL. Yes, just checking the market, but no rush for the newer fan since all is well and running cool. I agree with your approach and try to do the same when possible. Cheers

 

[Achmed]

Got some P/Ns?

Fan: $32.00 shipped: http://cgi.ebay.com/ebaymotors/PROCOMP-14-INCH-ELECTRIC-COOLING-FAN-14-CURVED-PC-2053_W0QQcmdZViewItemQQcategoryZ33600QQihZ013QQitemZ230257138359QQrdZ1QQsspagenameZWDVW

Relay: $3.00 at most auto parts store (40 amp/4 pole relay)

Fan Controller: $17.00 at O'Reilly Auto Parts or http://www.speedwaymotors.com/p/2350,370_Adjustable-Electric-Fan-Control-Kit.html

 

[hubs97xj]

Excellent, thanks.

 

[sunburned]

Fan: $32.00 shipped: http://cgi.ebay.com/ebaymotors/PROCOMP-14-INCH-ELECTRIC-COOLING-FAN-14-CURVED-PC-2053_W0QQcmdZViewItemQQcategoryZ33600QQihZ013QQitemZ230257138359QQrdZ1QQsspagenameZWDVW

Relay: $3.00 at most auto parts store (40 amp/4 pole relay)

Fan Controller: $17.00 at O'Reilly Auto Parts or http://www.speedwaymotors.com/p/2350,370_Adjustable-Electric-Fan-Control-Kit.html[URL="http://cgi.ebay.com/ebaymotors/210-Degree-Fan-Thermostat-Temperature-Switch-Relay-Kit_W0QQcmdZViewItemQQcategoryZ33603QQihZ016QQitemZ260247406715QQrdZ1QQsspagenameZWDVW"]
[/URL]

I'm a real newb at wiring, any guidance on how to wire this thing up? Also, how does it know what the temp is? Does it have a built in thermocouple or is it connected to a stock sending unit of some sort?

 

[four_shot]

The speedway unit has a thermocouple that gets attached to the radiator.

I don't recommend this particular unit. The fan never cycled correctly when I used it on mine ( '86 XJ 2.8L). Plus, It corroded and failed altogether after a few years. I was really dissapointed in this unit.

You're better off using a thermostatic switch connected to a relay. I will say that the Hayden fan that I got @ the same time has held up pretty well. It's not the quietest, but well worth the price.

 

[Achmed]

I'm a real newb at wiring, any guidance on how to wire this thing up? Also, how does it know what the temp is? Does it have a built in thermocouple or is it connected to a stock sending unit of some sort?

It uses an aluminum temperature probe that mounts behind the radiator and aluminum weathers perfectly fine. I am not sure what unit the previous poster used, but you should not have any issues.

 

[dobbs571]

do you have the part number for the adjustable thermostatic fan controller from O'reilly Auto Parts they could not find one .Will they did but at 89 bucks I dont think so.

 

[hubs97xj]

How about this?

http://www.oreillyauto.com/EW3/Prod...x=0&didSearchFor=Fan Controller&currentPage=0

 

[dobbs571]

Tryed the link didnt come up .said no i d found

 

[hubs97xj]

My bad, they've got it setup so you can't look for anything without listing your vehicle specifics first, so the link won't work without doing that. Anyway,

It's the Hayden Cooling Fan Control, Item #3653. Looks just like the kit in the other link. $15.99

 

[Achmed]

Yes, thats the one I use. $17.00 or so after tax. I hooked up a 40 amp relay ahead of the Hayden Controller to lighten the electrical load. Anyway, once it is all wired and setup all you do it turn the adjustment knob to kick on where you want it to. It takes a few times of fine tuning to get it to kick on and off exactly where you want, but I have mine kicking on right around 215 and it automatically kicks off around 200/205. Its perfect for my setup and when I am moving down the road, it generally stays off until I come to a stop. I also installed my LeBaron hood vents today so it may need fine tuning once again.

 

[proskier101]

im looking at doing this when i move later this month(since i can walk to work then)


I do not plan on running a temp. sensor on it. I was thinking of running it to a relay and then to the ignition(for auto on) and then to a switch in case I needed to turn it off manually. It would also be one speed, high. Here in FL its 115 in the sun with humidity and the jeep gets around 220-230 at a stop light(I run the A/c though)

 

[hubs97xj]

Someone mentioned this in another thread, and with the SPAL PWMs being backordered nearly everywhere I've checked, I thought I'd put this up.

http://www.dccontrol.com/0820.htm

Another type of PWM, similar operation and with some extra gadgets, still a bit cheaper than the SPAL, basically. Works on just about any fan, and is also a variable speed controller. Pretty cool, I think, although I'm completely unfamiliar with this outfit. It appears that they cater more to the Ford crowd, although those running Jeeps with Taurus fans could probably put this to good use. Anyway, peruse and decide for yourselves, I guess.