rollz4kix

I live in Arizona & it's stupid hot here. I installed a cooler in Sept because of overheating. Well she purged on me again rolling down the hwy. I'm gonna bypass the Rad & see if that helps. Anyone run theirs like that?

DFlintstone

In cold weather that may help as a "trans warmer". Also not sure if the "Aux" cooler is up to the whole job in high heat. Probably good to set it right. Do know that is not high pressure. I've repaired my lines with fuel line and clamps with no issues.

Radi

That transmission was designed to run 200-220 degrees, right about where your radiator should be, however an aux cooler is most always a good idea.
I'd hit the trans pan with an infrared thermometer to see what the temp is.

Cooler lines aren't crushed? Vent tube isn't plugged?

DSFB 96XJ

I have a 96 xj that seems to have no transmission cooler only lines from radiator. I've seen post of running too cool can be harmful, but i live in fl and would like to add an aftermarket cooler. Any advice on to do so or not and about tow package option.

dmill89

^This, the "trans warmer" probably isn't too important in AZ, but what is the capacity of your cooler (BTU)? You'll need one with decent capacity in order to be able to keep the trans cool by it self with the radiator cooler bypassed.

dans98xj

I have been running mine like that for almost 2 years now and never had any problems with cold weather. Just make sure you get temperatures gauges for the hot side and cold side so you make sure that the cooler is working properly.
And you can monitor the temps as well.

JK253

The heat exchanger only holds a few ounces of trans fluid at best; I don't think bypassing it does a whole lot in terms of temp reduction.

Coolant runs around and through the middle of the tube -- trans fluid runs between the two walls of pipe.

DFlintstone

Neat pics JK253. That does have a bit of surface area for heat exchange though.

jpmarine6786

I've always heard that when the fluid gets over 200 degrees it starts to degrade because Dex 3 isn't synthetic. And all these charts online say a transmission should be from 120-180 degrees.

DFlintstone

Maybe that's celsius ? The coolant is often at or above 210*. You wouldn't run fluid you wanted under 180* through that to cool it.

IJM

The coolant leaving the engine may be 210*, but it's significantly cooler on the cool side of the radiator where the heat exchanger is.

jpmarine6786

Four wheeler.com claims the AW4s operating temp is form "125-176 degrees".
I'm also putting a cooler on my Jeep this week.

dmill89

The heat-exchanger isn't particularly large, but it is immersed in coolant which conducts heart much better than air can. Many vehicles have optional (or standard in some cases) engine oil-coolers that are nothing but a small sandwich plate between the filter and block/filter-adaptor with coolant flowing through it that is small enough to fit in the palm of your hand but provides substantial cooling (granted engine oil will generally be much hotter and thus have a greater heat-differential with the coolant than trans-fluid), if you are removing the OE trans-cooler (heat exchanger) from the loop you will need to make sure your aux cooler has enough capacity to compensate for it (if you have an aux cooler with enough capacity it can run cooler though since the air is cooler than the coolant, even in the "cold" tank), running an aux cooler that is too small and bypassing the rad can easily cook your trans if you aren't careful.


Any decent sized plate and fin cooler should do fine, but only larger tube and fin coolers (which are less efficient at conducting heat) will have adequate capacity.

DFlintstone

It seems you have a point>

175 Degrees: 100,000+ miles (Normal is typically 179 to 195 degrees)
200 Degrees: 90,000 miles
225 Degrees: 55,000 miles (Pressure Drops)
250 Degrees: 25,000 miles (Valves Stick)
275 Degrees: 17,000 miles (Varnish Forms)
300 Degrees: 4,000 miles (Seals & Clutches Burn)
325 Degrees: TRANSMISSION FAILURE

That's from here> http://myautomatictransmission.com/t...ture-chart.htm

DSFB 96XJ

jpmarine's post about dex 3 not being synthetic. I'm about to do a rear seal and pan gasket change on my xj with ovet 200k. I was gna do a flush with regular stp dex then put valvoline maxlife synthetic for permanent. Is this a good idea.i have no tranny cooler either n live in fl heat