Electric vs Mechanical fan

[Miraphone186]

Hey guys, I was installing the new radiator in my G wag and the shroud for the mechanical fan broke in two when I was removing it. This got me thinking, I could get another fan shroud, or maybe I could buy an electric fan from bjs and bolt it in. After some research, it seems that mechanical fans cool better on the highway, while electric fans do better at low speeds, and because I'm going to be going on both the highway and doing some low speed offroading which one would be the best overall? I've also considered running both, but i'm not sure if they'll interfere with each other or not.

[Tinkerjeep]

you will likely not fit both an electric puller fan and the mechanical fan. You can mount a pusher fan in front of the Rad...but you probably have a bunch of other coolers and crap up front already.

Which is better? For efficiency -the stock mechanical fan. it requires no wiring, no fuses, no relays , no temp switch and does not pull charging load from the alternator. No special mountings etc.

I ran dual electric fans (not sure what they were out off) for a few years and finally got tired of the noise and electrical draw on the 140 amp Alternator at idle when running in extreme cold, with defroster, headlights, heater-fan motor at full-on and wipers on...at idle. Its too much amperage draw and the belts would slip, squeel.

You could maybe pull it off if you don't run alot in cold/dark/wet situations.

I'd try to get a shroud and just run the stock mechanical fan. It works great when the clutch is working properly.

[joe]

This'll prolly turn into a mech-vs-elec piss'n match but I'm a firm believer in steel solid mounted(no clutches or silly flex stuff) fans properly spaced under the shroud. If your cooling system is clean and in good condition with the proper coolant you don't need electric band-aids. If replacing the radiator I always toss in a new pump at the same time. Get your cooling system back to stock spec, then maintain it, flush swap in fresh coolant every two years and your golden. I don't rock crawl but worked the summers (geology) in AZ, NV, ID, OR, UT etc deserts with lots of slow speed low gear use and never had a cooling issue. Yeah a solid mount mech fan is a perceived HP drain but I don't run 4000 lb 4x4's at the drag strip so I don't care about HP numbers.

[Tinkerjeep]

Joe's right in one regard -removing the clutch does remove a potential complication...but its there for a reason.

most of the non-clutch mech fans I've seen are four bladed. Jeep fans are 7 bladed...

but pick your poison.

[serehill]

Joe has good points

It clearly depends on what you do. Fans have no use at highway speeds. Your HP drain is minimal. Electric fans a band aid? I wouldn't say that although I don't use one. I still have the clutched system. It works fine. Been a lot of great write ups about fans. If you don't have a perfect system it really doesn't matter. Mine doesn't have a shroud either. Probably not recommended but it works fine. I like the guys that set up pusher @ about 225 degrees come on for back up. That can not hurt. But that is just me. If I were to run pure electric I would run 2. Not 2 small ones, 2 that would operates the vehicle with one working. My standard fan with the clutch has never let me down so I've never gone there. I do have to agree the main reason I haven't is because of the electrical clutter. Out in the middle of nowhere more complicated isn't good. Then again that may not be your game.
Figuring out what you want to do is half the answer.
I really don't understand that belt squealing issues on a 140 amp alternator. Obviously something else is wrong tons of vehicles are running fans on 80 amp system & less. A properly engineered systems wouldn't have issues like that.

[jeepfan93]

Ok how about this. I have run both. Once with electrics to see if it really helped, once as a band-aid. And the stock mechanical with the stock clutch and severe clutch. I will tell you this, if your going to run electrics, even the cheapie Ebay ones like I did, you need to make sure your electrical system is up to it. So price of the fans, making a shroud, upgrading alternator and wiring, relay and wiring for fan. Making 100 hp more? No. And your out $300 that you can use for lighted tire valve caps. Severe duty clutch, barely stop turning, very loud and annoying to me. I don't have a quiet stock truck. $65 for clutch. You have a new radiator. Are you fighting an overheating issue, or is your stock one done. I have an aluminum radiator, with the stock clutch and I can't get up to full temp. Get it now? spend the $50 for another shroud and be done with it. This comes form a guy who SWORE the stock cooling system couldn't do the job.

[mrtazwrench]

On a future build I'm looking to go electric, but that is because I'm using a 4.3 GM engine and the shroud would have to be a large most likely custom piece to work with a mechanical fan... and I don't want to hear the laughter over putting a 4.3 in a FSJ, I'm using what I have (Wife's old DD S-blazer) and building a J-cab something maybe even on a Wag frame for my oldest Son who will be old enough to drive in 3 years, don't want a first vehicle with a ton of power either.

[Rich88]

This'll prolly turn into a mech-vs-elec piss'n match but I'm a firm believer in steel solid mounted(no clutches or silly flex stuff) fans properly spaced under the shroud. If your cooling system is clean and in good condition with the proper coolant you don't need electric band-aids. If replacing the radiator I always toss in a new pump at the same time. Get your cooling system back to stock spec, then maintain it, flush swap in fresh coolant every two years and your golden. I don't rock crawl but worked the summers (geology) in AZ, NV, ID, OR, UT etc deserts with lots of slow speed low gear use and never had a cooling issue. Yeah a solid mount mech fan is a perceived HP drain but I don't run 4000 lb 4x4's at the drag strip so I don't care about HP numbers.

X2. I have rock crawled in lo-range in desert heat and never had a problem, and it was because stock radiator, fan clutch, shroud, pump & coolant were all up to snuff.

Also, you'll have an HP drain whether its an e-fan or mechanical. When the alternator is working harder to supply the extra current, it has an increased mechanical resistance that the engine feels through the belts. When you spin an alternator by hand on the bench you feel no resistance. But when its in place, hooked up and loaded down, there's plenty of resistance.

[Miraphone186]

I couldn't care less about horsepower drain, I'm just having issues with cooling when I'm sitting. If I sit long enough the temps just go up and up and up until it overheats. It did this before with the crusty old stock rad too. The water pump and fan clutch seem to be good, but maybe not. I'll check it out tomorrow.

[blazer3664]

Factory cooling system with everything in good condition, should be fine. That is the key here, is everything in good condition?

To me (off-roader) the biggest reason for electric fans would be for water crossings so I can shut it off. Run a stock fan in deep enough water it will try to eat the radiator, not to mention bending the blades a lot of times.

Another place they are useful is for other coolers mounted where the stock fan dont pull air across them.




Back to your heat problems....

If your cooling system is OK, check to be sure your engine isn't running lean. An engine that is running lean will generally produce more heat, and can contribute to overheating.

Jim

[jeepfan93]

Thats what I'm getting at. Let's get the to the bottom of this. Motor specs? Replace T-stat? Flush system?

[mdcptman]

Count your fan blades, there should be 7. The DPSO had put a 6 blade fan on mine. It was fine if I was moving, but sitting traffic, it would slowly creep up temp till it overheated. The fan blades should also be cupped, not flat. I had replaced EVERYTHING in th cooling system, and the timing and carb were perfect. And it still overheated. After changing the fan to a 7 blade, it will barely get to a proper operating temperature.

[Strode]

There's some very good reading here:

http://oljeep.com/rad/edge_radiator.html

[Tinkerjeep]

I really don't understand that belt squealing issues on a 140 amp alternator. Obviously something else is wrong tons of vehicles are running fans on 80 amp system & less. A properly engineered systems wouldn't have issues like that.

0F degrees, hard rubber belts and idle speed.sitting at a stop, waiting for traffic after just starting the truck with no block heater...so the cold cranking added up. plus a 140 amp alt doesn;t charge 140 at idle...especially if idle is 700rpm or less.

I'm not sure what amperage draw my dual side-by-side fans were, but running two of them off the alt output post through twin 30 amp fuses and twin 30 amp relays to a common switch just to be safe... anyway...they just added complication and load to a cold battery/alternator. They cooled real well when I remembered to turn them on!

I do not have a fan shroud on any Jeep I own (they all broke and I never could find cheap replacements... I thought the factory ones were crap anyway. I plan on running one in the 401 J4X truck someday, but I'll fab it out of thin Aluminum most likely.

Right now the 401 does not overheat...but I have no AC or anything in front of the rad, and I don't go crawling in low gears in the desert. Haven't done any real off-roading for a long time, in this truck. Gotta fix a balljoint and get my new tires on before I do any again.

[serehill]

Interesting

0F degrees, hard rubber belts and idle speed.sitting at a stop, waiting for traffic after just starting the truck with no block heater...so the cold cranking added up. plus a 140 amp alt doesn;t charge 140 at idle...especially if idle is 700rpm or less.

I'm not sure what amperage draw my dual side-by-side fans were, but running two of them off the alt output post through twin 30 amp fuses and twin 30 amp relays to a common switch just to be safe... anyway...they just added complication and load to a cold battery/alternator. They cooled real well when I remembered to turn them on!

I do not have a fan shroud on any Jeep I own (they all broke and I never could find cheap replacements... I thought the factory ones were crap anyway. I plan on running one in the 401 J4X truck someday, but I'll fab it out of thin Aluminum most likely.

Right now the 401 does not overheat...but I have no AC or anything in front of the rad, and I don't go crawling in low gears in the desert. Haven't done any real off-roading for a long time, in this truck. Gotta fix a balljoint and get my new tires on before I do any again.

That's what I thought it still sounds like something wasn't right. I've got a mustang with dual fans & the alternator does not pump out 80 amps at idle either. I've seen it idle 45 minutes with both fans no problem. They both run perfectly at idle with ac on which is drawing max amps without squeal. I don't think there's anything wrong with electric fans but the subject was if your doing it because your standard cooling suystem ain't cuttin it something is wrong.
I don't run a shroud either but I do run an aluminum radiator. I totally agree you can't run electrics with the stock system forget it.