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

[comanche91]

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.

Yeah, I looked at those, but I saw many complaints on shipping delays, and a few reliability problems. Didn't know the Spal PWM controllers were on backorder, but that in itself says something, they are being sold. I have received nothing but good prompt tech support dialing my PWM in, and it's working exactly as advertised.

 

[markw]

Bingo. I would rather have a simple fan switch compared to a controller. Theres absolutely no need for the fan to have two different temp settings or fan speeds. Case in point: every car mfg that has dual electric fans uses a switch.

Your aux fan is controlled via the ECU, through a relay, no switches.
Ideally I think setting the spal to 200 low and then it gets a 220 high would work pretty good. I was thinking about doing this also. It looks like the tabs on the radiator aren't the same distance so you can't just drop another aux fan in the holes for the shroud? I'll have to look at mine tomorrow.

 

[hubs97xj]

I'm a fool for anything with knobs and variable color displays. I may give the cheaper unit a try if I can get one in a reasonable amount of time. I don't like the jumper setup, but wiring a pot in should be pretty simple, and would give it a good range of adjustment. Still looking for a SPAL unit, as I think you've got a point.

And then again, I may say to heck with it, and just order an adjustable controller and fan from Summit. We shall see.

It looks like the tabs on the radiator aren't the same distance so you can't just drop another aux fan in the holes for the shroud? I'll have to look at mine tomorrow.

At least on my 97, the shroud of a 97 OE efan would have to be modified to fit next to the stock efan. I can't even see the mounting tabs, with the shrouds and what not still on, but I suspect it's just like Comanche's. However, you can order the ziptie mounts and rubber bushings to sit against the radiator, at least with all the aftermarket fans. I suppose the same could be done with a little creative assembly of an OE fan, but so far, it's the same money for a used OE 97 fan as it is for a brand new aftermarket fan. I think the latter is the route I'm going to go, unless I score at the JY.

 

[Blaine B.]

Looks too close to the pully, unless you are using a different style of motor mount (MORE, Browndog, etc....)

The stock rubber motor mounts can allow alot of forwards and backwards movement.

Nice setup though!

BTW, there are 8 blade and 10 blade S style fans. The 10 blade are the best out of all 3 (Square blade, 8 S blade, 10 S blade)

 

[comanche91]

Looks too close to the pully, unless you are using a different style of motor mount (MORE, Browndog, etc....)

The stock rubber motor mounts can allow alot of forwards and backwards movement. Nice setup though!

BTW, there are 8 blade and 10 blade S style fans. The 10 blade are the best out of all 3 (Square blade, 8 S blade, 10 S blade)

I've since put in the button head low clearance pulley bolts and an 8 blade fan from a 96 XJ which is about 1/4" thinner. So the clearance now is a bit over 3/4", no worries.

 

[comanche91]

Ideally I think setting the spal to 200 low and then it gets a 220 high would work pretty good. I was thinking about doing this also. It looks like the tabs on the radiator aren't the same distance so you can't just drop another aux fan in the holes for the shroud? I'll have to look at mine tomorrow.

Those are exactly the LO and HI settings I'm using. So far, after a lot of driving, the fan is either OFF or on LO for 90% of the time. Stuck in slow moving traffic, the fan occasionally goes to HI, then the temp drops quickly below 200. I have not had to use the existing aux fan. It really is working well.

No, you'll need to dremel (or weld) two new slots in the bottom rad support closer to the radiator so you have adequate clearance from the fan head to the mech. fan pulley.

 

[hubs97xj]

I think I've found a fan donor vehicle. Now, I'm curious. I haven't been able to tear mine apart yet, but maybe you can answer this in the mean time. It looks like you used a spacer on the driver's side mount of the replacement fan (where it normally attaches to the wider part of the radiator assembly when in the factory location). About how much clearance between the fan and radiator is there on the fan? Can the shroud on the fan be trimmed back to net a little more clearance from the pulley?

I bought some stainless hardware with some fairly thin heads on them (couldn't find button head, just hex), and I'm hoping I can do a bit of tweaking/trimming to clear everything, but the fan to radiator clearance will be the deciding factor.

Thanks,
hub

 

[comanche91]

I think I've found a fan donor vehicle. Now, I'm curious. I haven't been able to tear mine apart yet, but maybe you can answer this in the mean time. It looks like you used a spacer on the driver's side mount of the replacement fan (where it normally attaches to the wider part of the radiator assembly when in the factory location). About how much clearance between the fan and radiator is there on the fan? Can the shroud on the fan be trimmed back to net a little more clearance from the pulley?

I bought some stainless hardware with some fairly thin heads on them (couldn't find button head, just hex), and I'm hoping I can do a bit of tweaking/trimming to clear everything, but the fan to radiator clearance will be the deciding factor. Thanks, hub

Yes, I used a spacer on the drivers side of the new fan. I also used the same mounting hole in the cross member that the original mechanical fan shroud used. This moved the new fan over to the drivers side and the fan head clearance is a good 3/4" from the pulley with the button head bolts. I had to order the button head bolts from Fastenal, and have plenty left over if anyone needs some. And yes, I did trim about 1/4" from the new fan shroud only because I didn't want the shroud touching the radiator core, not for pulley clearance. Pulley clearance is determined by the new fan mounting flages bolted to the cross member. Using zip ties and butting the shroud against the rad is an accident waiting to happen IMO.

 

[hubs97xj]

Okay, that's useful info. I've seen a few fans which included a rubber gasket/flange which they claim prevents the shroud from beating the radiator to death. If I can come up with something I've got a lot of faith in, I may fit it flush- if not, I'll trim it to clear, I guess.

I think I'd take some of those buttonheads off your hands if you wouldn't mind. Did you have to buy the bag of 100? I think I've still go my Paypal account, so if you want to part with 4 or half a dozen, PM me what you'd like for them and we'll sort something out.

Thanks,
hub

 

[comanche91]

Okay, that's useful info. I've seen a few fans which included a rubber gasket/flange which they claim prevents the shroud from beating the radiator to death. If I can come up with something I've got a lot of faith in, I may fit it flush- if not, I'll trim it to clear, I guess.

I think I'd take some of those buttonheads off your hands if you wouldn't mind. Did you have to buy the bag of 100? I think I've still go my Paypal account, so if you want to part with 4 or half a dozen, PM me what you'd like for them and we'll sort something out. Thanks, hub

PM sent.

 

[four_shot]

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.

the thermocouple weathered well...It was all of the relay and temp control electrics inside the case that corroded and failed (miserably). None of which was replaceable individually. It isn't weather sealed so northern Illinois winters just ate it for breakfast.

Just my two cents

 

[hubs97xj]

I'm getting ready to do the same basic swap (although using a Procomp 2053S fan and Flex-a-lite 31165 Variable Speed Controller), and have a couple of questions. I don't know if this has been tried by anyone in , as a search yielded no useful results, so here goes.

Other controllers use LEDs to indicate function, and in the case of the DC unit, relative fan speed (LED color varies by voltage, I presume, and I believe it's connected to the outputs in parallel, with 2 wires run directly into the cab to act as a simple display), in addition to the LEDs on the units themselves, ala SPAL, DC, and another... Pac, perhaps? I'm considering doing this with my controller, since I'll be snaking some wires in from the engine compartment for ignition control, and the override switch. Anyone familiar with LEDs care to comment? I haven't messed with them since... eh, suffice to say, a "while ago". I would think it would require some resistors to keep from roasting them, but aside from extending a harness or putting a stereo in, I don't normally do any "custom" DC electrical stuff. Any components I have laying around are all for very light duty stuff.

Anyone care to chime in here? Variable color LED connected remotely to a variable output (guessing 6-13VDC, 12-15A max), can't be too hard, even for me, but the power available tells me I need something to limit current to the LED... I think. I haven't played with DC in years.

 

[Boostwerks.com]

Geez. Some of you guys are making this way too hard.

Switch, relay, fan, and some wiring knowledge. Thats all you need.

 

[hubs97xj]

A simple, "That's way too complicated for me to figure out", or just not posting would have sufficed, but thanks anyway for that insight.

 

[comanche91]

I'm getting ready to do the same basic swap (although using a Procomp 2053S fan and Flex-a-lite 31165 Variable Speed Controller), and have a couple of questions. I don't know if this has been tried by anyone in , as a search yielded no useful results, so here goes.

Other controllers use LEDs to indicate function, and in the case of the DC unit, relative fan speed (LED color varies by voltage, I presume, and I believe it's connected to the outputs in parallel, with 2 wires run directly into the cab to act as a simple display), in addition to the LEDs on the units themselves, ala SPAL, DC, and another... Pac, perhaps? I'm considering doing this with my controller, since I'll be snaking some wires in from the engine compartment for ignition control, and the override switch. Anyone familiar with LEDs care to comment? I haven't messed with them since... eh, suffice to say, a "while ago". I would think it would require some resistors to keep from roasting them, but aside from extending a harness or putting a stereo in, I don't normally do any "custom" DC electrical stuff. Any components I have laying around are all for very light duty stuff.

Anyone care to chime in here? Variable color LED connected remotely to a variable output (guessing 6-13VDC, 12-15A max), can't be too hard, even for me, but the power available tells me I need something to limit current to the LED... I think. I haven't played with DC in years.

Hub, I would also like to have a remote LED indicator(s) in the cab to show the LO, HI, and OFF speeds of my new fan when my Spal PWM controller switches speeds. The PWM controller has a secondary fan output wire I may be able to use for this, and am verifying the signal out on this wire with Spal tech support. In checking it out myself, I see 6V when the fan first comes on LO speed, and 12V when it switches to HI, so I'm pretty sure this will work for me.

 

[hubs97xj]

After getting everything up and going, I don't think it will work with the FAL unit so easily. There's a single output, and about all I could manage without a great deal of work, is tying a relay to the outputs, and using that to switch a low amp circuit for a regular LED or lamp. That's one thing about the SPAL and DC units that eclipses the FAL. But, it works, and I've found a second leak, so fixing the system are going to take priority to further upgrading the system.

Here's the new setup.

Would have liked to use the shroud, but it wasn't going to work without a lot of trimming, and I had to have it together and running tonight. Project for another day, along with damming off the part of the fan that extends past the radiator. Project for another day #17.

Oh, and those buttonheads greatly improved the clearance. The picture sucks, but I'm not the least bit concerned about the pully and fan contacting, short of a wreck, and I'm going to try to avoid getting in one. Thanks, Don.

 

[comanche91]

A simple, "That's way too complicated for me to figure out", or just not posting would have sufficed, but thanks anyway for that insight.

:laugh: :laugh2: :laugh:

 

[markw]

Hub, I would also like to have a remote LED indicator(s) in the cab to show the LO, HI, and OFF speeds of my new fan when my Spal PWM controller switches speeds. The PWM controller has a secondary fan output wire I may be able to use for this, and am verifying the signal out on this wire with Spal tech support. In checking it out myself, I see 6V when the fan first comes on LO speed, and 12V when it switches to HI, so I'm pretty sure this will work for me.

It's not that simple. The spal puts out 12V all the time. It's just being switched on and off, or pulsed. The longer the on pulse, the faster the fan runs. Most multimeters can't really measure the output, you'd need an oscilloscope to look at it. The multimeter is going to show the average DC voltage.

Here's a decent explanation of it:

http://en.wikipedia.org/wiki/Pulse-width_modulation

Look at the "voltage regulation, and power delivery" sections.

 

[comanche91]

Thanks Mark, understand. I don't have a scope at home, so my multimeter was reading the DC average I guess. Having the indicator lights isn't all that important for me anyhow, as it's easy to tell by the fan sound.

 

[maalox]

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?