Transmission Cooler

[John Cox]

I’m replacing the transmission in my 1999 ford explorer 4×4. The transmission failed because it had both a bad torque converter and i overheated it pulling too much weight. I’m wanting to make this trans last a lot longer. My question is, would i be better off completely bypassing the factory trans cooler built into the radiator, or just simply add an extra cooler in line with the stock one? I tend to think that the tranny may stay cooler without 190 degree coolant from the engine heating it up. Please help.

Topic

[Charles]

Although a portion of the radiator is dedicated to the cooler, it is not directly exposed to coolant. Just add the new cooler In-Line and down stream from the existing. If you purchase an after market cooler it will have recommendations as to how it should be installed and where. If you are making your own from junk yard parts just review the instructions for the new after market parts.

[Mike]

When you overloaded your vehicle, was this a one-time thing or do you routinely haul heavy loads?

If it’s routine, you should be looking at getting a vehicle that can cope with the load, rather than trying to convert the wrong vehicle for the job.

[John Cox]

When i say over loaded, what i mean is for the current state of the transmission. My trailer towing cap is supposed to be 5500lbs, but the torque converter was already on it’s way out. The trailer might have been 2500. I was thinking of an aftermarket cooler with it’s own fan.

[Mike]

I used this site to look up the towing specs of the ’99 Explorer 4X4:

Explorer 2dr 4WD 4.0 V-6 4,900 a,d/e
Explorer 4dr 4WD 4.0 V-6 5,160 a,d
Explorer 2dr 4WD 4.0 V-6 2,220 c,f,i
Explorer 2dr 4WD 4.0 V-6 2,940 d,f,i
Explorer 4dr 4WD 4.0 V-6 2,720 d,f,i
Explorer 2dr 4WD SOHC4.0 V-6 3,380 a,n
Explorer 2dr 4WD SOHC4.0 V-6 4,380 a,c
Explorer 2dr 4WD SOHC4.0 V-6 4,880 a,d/e
Explorer 4dr 4WD SOHC4.0 V-6 5,680 a,d/e
Explorer 4dr 4WD 5.0 V-8 6,520 a,d

Notes:

a Requires automatic transmission and towing package.
b Requires 3.31:1 axle ratio.
c Requires 3.55:1 axle ratio.
d Requires 3.73:1 axle ratio.
e Requires 3.98/4.09/4.10:1 axle ratio.
f Manual transmission.
g Fifth-wheel towing.
h Automatic transmission.
i Must be equipped with heavy-duty towing package.
j Requires automatic transmission cooler.
k Requires 16-inch rims.
l Automatic rated slightly lower.
m Requires 17-inch wheel option.
n Requires 3.27:1 axle ratio.
o Requires 4.30:1 axle ratio.
p Requires 4.88:1 axle ratio.
q Requires 5.38:1 axle ratio.
r NGV = natural gas fueled vehicle

Your tow rating depends on how the vehicle is equipped. Hope this helps.

[John Cox]

Mine is a/e and sohc 4.0. Thanks Oh, and 3.98 axle.

[John Hugon]

Also…. make sure you flush out your transmission cooler that’s on your truck.

[transman304]

Put the cooler in line with the factory one. The trans is dependent on temp for functioning properly. Also like said before FLUSH your cooler in your radiator.

[John Cox]

I’m installing a low mileage used one from a salvage. Are there any upgrades besides the cooler that I should consider? Or just replace the front seal and rear seal ands stick it in?

[Mike]

I don’t disagree with any previous advice but I want to point something out that transman mentioned briefly.

Factory transmission coolers are actually not just for cooling, but for heating. Think of them a trans fluid temperature regulators. The fluid is meant to be heated as much as it is meant to be cooled. The coolant gets to operating temperature long before trans oil does, so they let the coolant warm the trans fluid to operating temperature quicker than it would normally. Since the coolant stays the same temperature all the time, the logic is that it will also keeps the trans fluid from rising above that ideal temperature even though it doesn’t always work out that way when the trans is heavily loaded.

[transman304]

I would go ahead and drop pan and put in new filter(don’t forget o-rings) look at the magnet for debris. New front seal is a good idea. Make sure converter is locked in the transmission! These are very easy to break pump gears in if not setted all the way in. 4×4 no rear seal,just gasket between ext. housing and transfer case. Good luck man.

[John Cox]

Warning the fluid up is not something I had considered. I’m glad you mentioned it. That makes a lot of sense!

[transman304]

Temp controls TCC apply and can even inhibit overdrive until set temp is reached.

[Donald]

For trans coolers I have gone the route of taking the outlet line off the transmission and using an external cooler then routing back through the radiator cooler. Keeps it warmer while still keeping temps down. Also another thing is there are transmission thermostats out there.

[John Hugon]

Fopeano wrote: Factory transmission coolers are actually not just for cooling, but for heating…

..
Very good advice…

[Gary]

Always route the cooler in series with the stock cooler. Fopeano is correct, you want to have the fluid get to operating temp so you run it through the stock cooler to get heated by radiation from the coolant, further to maintain that temp by cooling it . Add a thermostat and a bypass to allow it to flow through the additional cooler when the extra cooling is needed. This is the ideal setup to maintain a good temp, not to hot or not to cold under all operating conditions.

[Author]

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