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AW-4 Transmission temprature. What's yours?

W

Wiskey

NAXJA Forum User
Location
San Marcos
Hello all!

I've had transmission problems since I bought my jeep,.. at first it presented as smoke pouring out of the back of my truck going up steep hills at freeway speeds. It took me a while to track this problem down, when I finally did I found that transmission fluid was getting hot enough to boil out of the dipstick tube, the pour down on the exaust.

So I installed a temp gauge - directly into the pressure port which is the hottest place I can put it, and quickly pinned it past 260 deg.

I installed twin transmission coolers - and found myself going 20 mph up hills coming back from Moab Utah just to keep the transmission under 240.

I have since re-geared and it does better now, running at around 190 in town, longer drives see 230, but that still seems hot to me.

I was wondering what temps your transmissions hit? is this thing just made to run hot?

Thanks,
Whiskey
 
you need to rethink your transmission cooler setup, optimum temp for the aw4 is 175-200 degrees F. maybe add a fan to one or both coolers. I read an article that said every 25 degrees you go beyond the maximum operating temp of the transmission cuts its life in half. you could be seeing those temps due to excessive slipping or problems with the torque converter locking up.
 
I have a cooler and temp gauge on mine. Unless I'm sitting in traffic in 90* heat or doing long climbs while wheeling, I usually never see anything even near 180*. Just normal street driving I'm sitting around 130-150 at the very most. In colder months on the street, the gauge just sits down near 100.
 
Sounds like you have more problems than just needing a cooler. AW4s are a dime a dozen, pick one up from someone selling on the sight and change it. Have you changed the fluid and trans filter, burned tranny fluid is no good for anything.
 
Yeah,.. every time I've gotten it really hot I've made a point of changing out the fluids. The filter is brand new, and I've never seen any metal in it.

I'm wondering if it's so hot because of where I'm reading the temp from?

Whiskey
 
Umm,.. Passenger side of the transmission about half way down it,.. near the NSS switch. I was going to put the sensor in the pan until a transmission shop told me not to be an idiot and just put it there. I don't know the thread of the fitting, but one of the adapters that came with the gauge fit it perfectly.

Whiskey
 
How do you have your coolers plumbed and where are they mounted?
 
Both coolers are on the front of the Radiator, they cover the whole front of it actually. They are plumbed in after the transmission line goes through the radiator.

The Rad itself is a Checker brand 3 core.

Whiskey
 
Wiskey said:
Where is your gauge installed Sunburned? Is it in the pressure port as well?

Thanks,
Whiskey
Click to expand...

Cut the hard line coming out of the trans going to the radiator and installed the gauge in a T-fitting. I have my cooler mounted in front of the radiator and plumbed in inline after the radiator cooler. Pretty much followed the writeup on Jeepin.com
 
As I understand it, yours will read much lower than mine due to the placement of the sensor. I might have to just get a heat gun and shoot my transmission pan to see how hot the thing is really getting.

Whiskey
 
i would think the temp gauge should be on the output line of the transmission. that will tell you how hot the transmission is as opposed to the input line telling you how cool the ATF is coming out of the cooler(s)
 
My sensor is mounted in the pressure port also, which is right next to the output line to the cooler. I have 2 coolers, one with a fan, and do not run through the radiator. Around town in the summer 80-90deg outside my tranny runs around 140 -150. Climbing mountain passes 180 maybe 190 if its really hot outside. In the winter time 125-150 max.

Sounds to me like you have some tranny issues. Check to make sure your torgue converter is actualy locking up. If the converter does not lock up the tranny will get hot fast.

From my 1995 Cherokee FSM "normal operating temp of the AW4 is 125-176 deg".

J
 
Last edited:
Regis Finn from B&M racing was on a radio show I listened to a few weeks back. For reference, he said to keep any transmission below 200 degrees F. He said for every 20 degrees you go above 200 you cut the life of the fluid down by 1/2. So 220 degrees = 1/2, 240 degrees = 1/4, 260 = 1/8, etc.
There have been a lot of differing views here about where to take a temp reading. I personally want to know how hot the fluid is in the pan because that's what's going up into the trans. Everything coming out (heading up to the cooler) is doing to be skewed by the torque converter temps, which can give you a false-high reading. My ideal setup would be a sending unit on each line (one before cooling and one after) and a switch so I can toggle between the two on the gauge.
 
The thread on the AW4 fittings is M14x1.5 straight thread (i.e. not a taper pipe thread) per a thread GrimmJeeper has going.

The cooler tubes that plug into the fittings are standard 3/8 steel tube, so you can simply go to home depot/any auto parts store, buy a 3/8 NPT T-fitting, two NPT to 45 degree flare fittings, some flare nuts, and a coolant temp sensor and screw it into the side port on the T-fitting and put the flare adapters on each end, then insert it in the line. If you have a 96 or earlier XJ you can then cut the wire to the coolant temp gauge and install an SPDT switch to select between the stock sensor (to measure coolant temp) and the sensor you just added (to measure tranny fluid temp), or you can mount a second gauge for the second sensor however you want to.

I've been meaning to do this for a long long time now but other things keep breaking and taking my time.
 
Wiskey said:
Hello all!

I've had transmission problems since I bought my jeep,.. at first it presented as smoke pouring out of the back of my truck going up steep hills at freeway speeds. It took me a while to track this problem down, when I finally did I found that transmission fluid was getting hot enough to boil out of the dipstick tube, the pour down on the exaust.

So I installed a temp gauge - directly into the pressure port which is the hottest place I can put it, and quickly pinned it past 260 deg.

I installed twin transmission coolers - and found myself going 20 mph up hills coming back from Moab Utah just to keep the transmission under 240.

I have since re-geared and it does better now, running at around 190 in town, longer drives see 230, but that still seems hot to me.

I was wondering what temps your transmissions hit? is this thing just made to run hot?

Thanks,
Whiskey
Click to expand...

I had the same problem, long time ago. I was on 33 and 3.55 gears, running the wrong type of ATF. I filled a AW4 with type F and it did the same thing. (boiled out the vent on steep grades) Was like spy hunter video game. huge smoke screen! I flushed it out with dexron and everything went back to normal, but that was two transmissions ago. AW4's go a long time.
 
Here is what mine runs at all the time.
P1020426.jpg
 
I run a large external cooler connected to the return, after the radiator, and an external filter adaptor on that side, I am using the port there for a sender for the cool side of the fluid, after watching engine and trans temps, I 've seen this;
They follow each other - if one gets hot the other does
The ONLY time I have ever had problems is when neither would cool down after a very long haul up a steep hill, once I got to the top, I shut down for about 15 min (I was watching everyone else anyway ;-) ) Going back down everything stayed very normal.
Normal is supposed to be 125-160 or so, It would be normal to see temps rise in traffic, uphill, or idling in traffic, if they come back down when you are moving it's fine. I would only be concerned if they stayed high and would not come back down over time.
 
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