Push or Pull

[jerrybromley]

I am planning to use an electric fan as my main cooling source for the radiator .( no engine fan)
I was wondering whether there is any advantage to setting the fan in front or behind the radiator . I have used them on past projects and have put the fan in front to give extra room around the front of the motor.

 

[chuck1022]

I am planning to use an electric fan as my main cooling source for the radiator .( no engine fan)
I was wondering whether there is any advantage to setting the fan in front or behind the radiator . I have used them on past projects and have put the fan in front to give extra room around the front of the motor.

Interesting question.

1. I am sure fans are naturally made to work most efficiently one way or another.

2. Once you figure out which way is most efficient,will it work for your purpose. Freeway...streets..offroad

Once I answer those...it usually opens up questions

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[spap]

I don’t know the answer, it I would just think that a pusher fan in front of the radiator could block air flow, but a puller fan behind the radiator doesnt have that blockage resistance.
But at the end of the day it is what fits and works

 

[needsmoarturbo]

If you put it in front I think you might have to ditch the latch and get hood pins due to available space if that sways your decision

 

[DirtDonk]

Basically a puller fan is said to be notably more efficient than a pusher. Even, apparently, one that's designed to be a pusher.

The other thing is, as stated you don't have enough room for a fan of any appreciable size in front of the grille. Even with cutting everything out it's a tight fit.
Two smaller ones "might" work better, but not that I've seen.

Even in the puller position we're limited in depth, which limits the power of the fan.
We have good ones that are working for many people (https://www.wildhorses4x4.com/category/Bronco_Cooling_Fans) but it's not a cure-all if you have an underlying heating problem to begin with.
That's why the Explorer setup is so popular. Aside from having a kick-butt mechanical fan, it also leaves a little more room for a bigger electric fan.

Paul

 

[sanndmann3]

Puller is more efficient. Air goes straight thru radiator before it gets to fan blades. it exits the spinning blades at an angle. If the fan was in front of radiator, the exit air hits the core at an angle, loosing efficiency. Thats my understanding of the situation...

 

[Broncobowsher]

Another reason a puller is more efficient, it drops the air pressure ever so slightly. That drop in pressure is like going up a mountain, it's a little cooler at altitude. But we are splitting hairs on this.

Be warned right now, Broncos in general don't like to be cooled with electric fans. The super amazing 2700 CFM special that only draws 8 amps is a complete joke in a Bronco. By nature of a narrow frame and a low hood height the radiator is a tad bit small. Normally the fix is a little thicker core and a good fan and shroud. That thick core is the issue. It's needed to get the capacity, but that thickness makes fans struggle to move air through them. It takes POWER to move the air needed to cool a Bronco. It's easy to get a belt driven fan to move air, afterall it is attached to a couple hundred HP supply that doesn't mind giving up a little. But in electricity you need watts to move air. Lots of watts, because watts are (horse)power. Since watts are amps times volts, and you are stuck running a 12V electrical system, you need lots of amps.

So what does it take to cool a Bronco with electricity? It has been done. It can work. There are some OEM fans that pull hard enough, the go to ones are Taraus and Volvo. They typically spike at 70A on startup and run pulling about 40A. To run this much sustained power you need an upgraded charging system, and an electrical system to handle that much upgrade from the better charging system. Can we say snowball?

The last Bronco I knew that worked with all electric cooling using all new parts had well over a grand into it. The fans, rated for high pressure drop to pull through a thick core, a custom made radiator and shroud. The electrical upgrades were already done so that isn't part of that price.

And then you find an Explorer accessory drive packages so well, has a nice thermostatic fan clutch. It is far enough away from the core that a proper fan shroud creates a Plenum that causes air to pull much more evenly across the core. And it just works great.

 

[jerrybromley]

Thanks for the input..........I made the mistake of assuming that the electric fans were as effective as the belt driven one. Broncobowsher's post makes perfect sense to me . My original thought was that even at slow speed I would get more air flow with an electric fan. My thought was that the fan speed would not be reliant on engine RPM

 

[DirtDonk]

They're actually really good on the trail and in traffic at slow speeds. As you suspect, they can really help there.
But one other thing that Broncos suffer from is poor aerodynamics. This forces the fans to do double duty at higher vehicle speeds as well. Because with all the high pressure air building up underneath the front end (and the more the Bronco is lifted, the worse it gets) and the high pressure air building up on top of the hood near the cowl (boxy shape) you get piss-poor natural air flow (scientific terminology of course) through the radiator like you would in a more modern vehicle. So the fan is critical at all speeds.

That's why electric fans are not a cure-all for an overheating issue. In fact, depending on what the underlying issue is, it could actually be worse.
I'm still a "fan" (pun sort of intended) but not for every situation. With my perfectly tuned modern EFI setup, small lift and very low gearing, I could probably get away with even a small electric fan. But not everyone can.

Paul

 

[rguest3]

Jerry - Has your Bronco been over heating? Or, just trying something different?

Make sure the Whole Cooling system is working up to par. Water Pump, Thermostat, no leaks, fan shroud installed and a good 17" mechanical fan or Explorer Set-up.

I have never had to install an Electric Fan, even here in Hot, Humid Florida.

 

[jerrybromley]

Rguest3.....I have no idea if she will overheat or not . The motor is in pieces from the machine shop under a tarp in my shop. (The machine shop recommended not assembling the motor until I'm ready to start it.) I am trying to plan ahead and buy just what I need . Otherwise I have a nasty habit of buying stuff and changing my mind . Just like this idea of using the electric fan instead of the belt driven. It sounds like I would have gone back to the belt eventually

 

[Broncobowsher]

Go get a box of Explorer accessory drive parts and throw them under the tarp. Problem solved for now.

 

[jerrybromley]

Go get a box of Explorer accessory drive parts and throw them under the tarp. Problem solved for now.

Interesting ,Broncobowsher... I have actually never considered that. I assume we are discussing a serpentine system. I have been of the mind set to keep looking like she did way back when . A serpentine system would not look so retro ...but if this is a vastly superior system... I have to look hard at it

 

[DirtDonk]

Tough call when you want it to look original. But it is in fact a vastly superior system in pretty much every way.

It's shorter for more room for fans. Either the fantastic mechanical fan with thermostatic fan clutch. Or even potentially for that larger electric fan someday. Of course that's not going to look stock in any way either...

At least some of the POSITIVES:

It easily mounts a fantastic 4G alternator with super solid mounting.

Has a pretty darn good power steering pump with remote reservoir that is pretty efficient at keeping aeration at bay.

Super water pump, that can be changed literally without removing anything else other than the single belt.

Has an A/C compressor if you either want on-board air supply or actually want A/C like I do these days.

NEGATIVES:

Doesn't look stock. But who cares if it fixes lots of other stuff.
You can't use any kind of a mechanical fuel pump with it so need to go electric if you haven't already.
Needs a slight re-orientation of the alternator wiring and the water pump-to-radiator plumbing.

That's about it for the negatives. Can't think of any reason not to run one, other than it's more work the first time and it doesn't look stock.
There's really no reason your stock setup in good condition can't work though. Unless it has deteriorated and you don't renew the parts, or you're building too much heat for the system either from higher horsepower, harder use, or underlying problems with the engine and it's state of tune.

So basically you still have a choice. But the Explorer setup was/is Ford's most modern iteration of our basic cooling system.

Paul

 

[jerrybromley]

Thanks for the breakdown Dirtdonk ( no pun intended ) I have not yet made this decision. I have no intention making this truck some kind of horse power monster.

I have purchased a rolling chassis that may get a more performance oriented build. So even if I decide to go stock with this Bronco the next one will benefit from this wealth of information

 

[Revelation]

Have seen the Tarus 2 speedfan in action, it was mounted with the Tarus shroud and temp sensors, when it kicked on hi man the motor temp dropped quick!