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Improving Engine Cooling


e21pilot

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I am looking at what I can do to improve the cooling on my 1992 4.0/auto extended cab Ranger. It generally runs cool except when towing. One thing I notice is that while the clutch fan looks to have the stock shroud around it, the fan sits almost in the open, closer to the water pump and not entirely in the circular part of the shroud as I have seen on other Ford engines. I would think this would reduce the fans ability to pull air through the radiator. I wonder if other 4.0 Rangers/Explorers are like this as well or is there a taller shroud out there or perhaps a factory clutch fan spacer that is missing on my rig?

I am also planning to add a transmission cooler in front of the radiator and want to get as much air moving through it and the radiator as the fan/shroud will allow to avoid having to add an auxiliary electric fan.
 


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RonD

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The back 1/2 of fan blades can be uncovered by shroud, that's normal
Fan pulls air, so as long as the front of the blades are inside the shroud it will pull the air thru radiator

Its possible radiator has some blocked passages, so you are not getting full cooling or full coolant load(gallons)
Radiators provide a 15deg temp drop driving slowly, or at idle and 20deg drop at speed
If you have a temp gun you can test upper hose vs lower hose temps at warm idle

It is normal for temp gauge to sit just above 1/2 when pulling a load or even going up a long grade with no load
Center on gauge is about 205-210, normal temp is 190deg, so just below 1/2, just over 1/2, 220deg is not that bad
 

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First you should definitely add a bigger trans cooler if you want to keep your auto alive.

Secondly, you probably already have the big radiator, so that's good... should be about 2" thick... if not, you can upgrade to that. Additionally you have three choices of fan clutches: normal, heavy duty and extreme. I've tried them all and prefer the heavy duty one. The extreme duty locks up too soon for my taste and will really hurt your gas mileage - although maybe it's necessary for towing in your case, I don't know.

As far as the shroud goes, the "rule" I'm aware of is that the engine side of your fan should stick out of the shroud about half an inch (roughly.) Apparently that allows it to pull air through and have it exit the shroud... if the fan is too far in, it kind of just cavitates inside the shroud and if it's too far out, the fan won't pull air through it, just gets blown around in the engine bay.

If your shroud isn't as it should be, you can find others at junkyards to play with.
 

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Add some soap or other surfactant to the coolant. This will break up the surface tension of the water in the coolant allowing it to mix better with the anti-freeze solution and transfer heat to/from the metal parts of the cooling system more efficiently.
 

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As above, or you can buy such stuff as Water Wetter or Purple Ice. I use Purple Ice in all my vehicles.
 

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As above, or you can buy such stuff as Water Wetter or Purple Ice. I use Purple Ice in all my vehicles.
Yes, those products would fall under the auspices of "other surfactants".
 

cbxer55

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Purple Ice claims 25 degrees cooler. That's a BIG claim. Don't know if I believe it. But, I don't believe there is a downside to using it either.
 

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e21:

First off, how about an Electric Fan??? Taking the crank shaft driven fan off any auto I have ever owned has ALWAYS reduced the load on the engine enough to produce better fuel economy.

An engine oil cooler is a WIN/WIN!! It adds more cool lubricating fluid to your powerplant and has the potential of disapaiting more heat. With more oil, it will also last longer, saving money on oil changes.

You can raise your hood in the rear with 3-5 washers to let under hood heat escape better. Pretty cheap but effective.

The transmission cooler shouldn't even be a question, how about 2 ..)

Headers also do a good job of;

improving exhaust gas velocities, thereby lowering under hood temps; lowering underhood temps mean less ambient temp affect on the transmission.

increasing torque, thereby increasing fuel economy and potentially reducing engine work, thereby reducing ambient temps affecting the transmission.

The sole change that has not only increased my fuel economy but reduced engine and transmission operational temps is the removal of the crank shaft driven cooling fan and clutch for an electric fan...just like all the new autos have???
 

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Before spending money modifying anything, look at your radiator cooling fins and make sure they aren't corroded or coated with road grime.
 

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I'm all for electric fans in place of the mechanical clutch but the PCM has to have complete control over the fans operation. An aftermarket setup won't engage/disengage when required to for the sake of A/C if the PCM doesn't have the programming there to control it.
 

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Pretty easy to add a relay to activate an e-fan when AC Compressor get 12volts

And I agree, E-fan is a win-win, on any engine
 

e21pilot

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Lots of good suggestions here. I'm going to start by seeing if I can borrow the infrared camera from the insulation contractor and take a pic of radiator just after the thermostat has opened for a bit. It is an old radiator and it possible it is not working completely. I believe there is a slow coolant leak in the corner of the radiator so most likely I will start my mods there and make adjust the shroud as necessary to get the fan a little more inside of it. I also contacted Derale and they suggested a trans cooler that might help a lot as well. Speaking of trans coolers and transmission cooling lines, I notice mine are very rusted. I was thinking of replacing them when I install the new cooler. Am I correct that these are just 5/16" tube or perhaps are they a metric size? Is 304 thin wall, stainless tube sufficient for these lines? I might get some tube and borrow a bender and flaring tool and see if I can make up new lines based on the old ones. If I go that route, is there a good source for stainless fittings that would match the factory connectors at the transmission and the radiator?
 

55trucker

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Pretty easy to add a relay to activate an e-fan when AC Compressor get 12volts

And I agree, E-fan is a win-win, on any engine
That's not really the issue...

on any vehicle that is OEM equipped for e-fans the PCM will disengage the fan when it is not needed with respect to vehicle speed, one can't get that flexibility with an aftermarket arrangement & a PCM that is not e-fan equipped, and that's the major reason why I haven't done so.
 

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That's why you use a temp switch?
I don't think any factory e-fans would have a speed on/off, because speed while pulling a load is not relevant just temp is, or going up a steep grade
And if there was a tailwind then less cooling at any speed, lol
So on/off is strictly a temp thing

Most factory e-fans run full time when AC is on to keep better air flow thru condenser in front of radiator
And WOT relay cuts AC compressor 12v so would cut e-fan as well unless temp switch was on

As long as temp switch was well placed and set correctly I don't think there would be much difference from factory setup
And some factory setups run the e-fan after key is off as well, something you could do or not do
 

55trucker

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Actually both the *new* '18 Escape my wife & I purchased & the '91 Grand Prix we own do this, where A/C is concerned the GP cycles the fans when the vehicle is stationary or near stationary & in the case of the GP anything above 70kmh(45mph) the PCM cuts the power to the fans altogether, the Escape does so at 80kmh(50mph) & as you pointed out at WOT the fans are eliminated unless the engine heat is at the temp threshold for engaging.
The key off feature would be a nice asset in the GP, that huge engine fills the engine bay & heat has very little place to escape.
 


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