Transmission cooler, Need or not?

[Bikeflyer]

I was suprised to see how cheap these are, but I need to know whether or not this is a need or just 'bling'. I do highway trips, which in Pa are rather hilly, and I have a 2500 lb GVW trailer which I tow a fair ammount, sometimes on said trips. I heard these transmissions can overheat, so I was wondering if I should be looking that way. It also has a remote filter kit, which sounds like a nice idea for more frequent changes, but again, Is that bling or need? All I want is simple and reliable.

http://www.amazon.com/70264-SuperCo...-Cooler/dp/B000CIIDZE/ref=pd_bxgy_auto_text_b

 

[HoosierJeeper]

If it's a frequent thing, I'd definitely get a cooler. If it were a one or two time thing, you'd be fine, but otherwise, no....

 

[Bikeflyer]

The thing is I do 2 or 3 short local hops with the trailer a week and maybe over-the-road with it every couple months, but they tend to be in the mountains. The counterpoint is I have a rain/sleet/snow job which means I have to brave some serious cold (like 0-10 deg in winter) also. I have heard this can pose an issue to a coolered system. Is this true?

 

[Powerslave]

A transmission cooler for Chrysler/Dodge transmissions is ALWAYS a good idea.

 

[kj924]

A ****** cooler is never a bad idea, especially when you are hauling 2-3 times weekly like you said. In the winter, it would not be a issue.

 

[tjkj2002]

Doing a correctly setup trans cooling system is always a good thing,seting up a bad cooler setup can be bad for your trans in colder temps and ineffective in hot temps.

 

[Bikeflyer]

What defines good or bad?

 

[sleeve]

First let's start with what model year KJ you have... 2005. In 2005 the cooler was a stand alone unit mounted in front of the radiator / AC condenser pack. So you technically have a "aux" cooler at the moment. To improve the transmission fluid cooling capabilities I would recommend that you install a 2002 KJ radiator with the built in trans cooler and then tapping that cooler into your existing factory "aux" cooler. This will increase your cooling capacity, reduce temperature spiking of the fluid and improve your transmission fluid warm up time. You can also consider a small pusher fan mounted on the existing cooler - but adding the radiator cooler is my recomendation. The only question I have is on the lines - if they are all hard line you might need to tee off very close to the factory aux cooler.

There have been some discussions on this before though - here is some light reading: Improved Cooling Thread,
Some nice points on cooling temp and trans cooler variations by year,
Older thread on the cooler situation

I'm sure there are more threads but this should get you started on the path to properly cooling the transmission fluid and keeping your vehicle on the road longer.

 

[Dave]

Lock out O/D if towing in hilly areas and that will keep the ****** cooler.

Dave

 

[Bikeflyer]

So if it has one already(I looked and it seems to), then the question is then, do I need an additional cooler or is the stock setup acceptable for my trailer usage? Also, has anyone put on a trans-temp gage?

 

[sleeve]

If you leave your cooling setup stock and simply turn off the Overdrive while trailering your KJ should live a long and happy life. If you are still looking for an improved solution over the stock setup I would recommend mounting a small electric pusher fan on the front of the transmission cooler that is thermostatically controlled by using a product similar to this Thermatic Fan Controller or this unit Delta Current Control - Fan Controller. [*note the DCC system is hand built and it'll take about 4 weeks for delivery] This way - you don't have to worry about switching on the fan while towing or even while driving because it will just turn on all by itself when it's needed and thus help to keep your fluid temperatures under control.



Now, personally I believe the stock cooling is acceptable. The one downside to the cooling setup follows: Since the cooler is mounted on the outside without any larger metal heatsink that functions as a secondary cooling device - the external transmission cooler can reach a point where it can only reject a certain (maximum) amount of heat from the fluid. All other heat, above that maximum will be returned back into the transmission fluid since it can not be placed anywhere else. This is what I would consider a temperature spike. This typically would occur at lower speeds where the air moving across the cooling fins of the unit is at it's minimum and the load on the transmission is greatest [towing].

If we consider the in-radiator version of the transmission cooler we can see that the extra radiator surface can continually accept the extra "burst" of heat from the transmission fluid and properly dissipate it across that much larger metal heat sink [radiator surface area] effectively aiding the transmission cooling capability. This then controls the spikes in transmission temperature more effectively than the remote mounted cooler found on KJ's equipped with the 42RLE transmission [2003+ KJ's].

Now with all of this stated - turning off the Overdrive really cuts down on heat generated while towing and given the number of KJ's running around on the road with no problems with their transmissions, it is safe to assume that the current setup is, again, acceptable for normal use.

 

[Bikeflyer]

Thank you. That pretty much explained it.

 

[n8fis]

I once seen a ****** cooler set up with a bypass valve installed.
The cooler was bypassed during winter months if no heavy loads
were going to be pulled.