I have an '04 F150 SuperCrew, FX4, 5.4/V8, with towing package. I have a mechanical Autometer tranny temp gauge installed into the tranny fluid pan.

I tow a camper weighing under 6000 pounds. While towing this weekend (the first real test since installing the temp gauge), the tranny temps were always in the 190-210 range. Outside temps were 80 to 100 at altitudes of 6000 to 10000 feet, and almost constantly uphill or downhill.

Are these temps too high? Am I getting "heat soak" from surrounding heat sources due to the location of the temp probe and wiring? If so, is there any estimate of how much lower the actual tranny temp is? Am I killing my transmission?

You may have guessed from my questions that installing the tranny temp gauge is the most mechanically advanced job I've accomplished with the truck. So, use small words, please.

doug

 

The answer to your question is quite open to debate.
I have experience with this on an 02 super crew 4.6 towing over 5k lbs (total over 11,000 lbs GVCW).
Here's some things I have come to see about transmission temperatures.
Your looking at pan temperature that is not the hottest location in the fluid flow.
When the trans is out of lock, the convertor is shearing the fluid and generating the most heat at that point and in the output line to the radiator.
The fluid temps can at times of low load, be lower than the engine cooling system and actually be raised in temperature by the radiator then cooled back down by the aux cooler.

With 210* showing in your pan, you would get very concerned about the temp in the output line you would see if the gauge were in that output line. You would probably see over 240*.
So the question is at what point should the temperature be monitored?
In my setup, I use two coolers, bypass the radiator and monitor in the output line close to the transmission.
I see about 220 in the output line and about 148 in the pan with my present setup.
I an doing ongoing research using an infrared heat gun and found something I was not expecting.
It goes like this. The output line is the hottest, the input to the first cooler is nearly the same, the output from the first cooler drops about 20*, the output from the second cooler about 20 more *, while the pan will be at close 20* hotter than the outlet of the second cooler.
But what happens is I am cooling the fluid below pan temperature at the output of the second cooler.
Bottom line seems to be that we cannot cool the fluid below the normalized transmission pan temperature because the normal operation of the transmission, the engine heat back through the case etc. prevent cooling the pan below a certian level unless there was some form of more cooling and the volume was increased to make the pan temp come lower. This would seem difficult to do. Also consider that the lowest temp you can go to depends somewhat on the outside temp and at what temp the trans runs at under light loading and in lockup long enought to find it's coolest running point while driving.

So 210 in your pan would be ok in my opinion but a bit on the high side from what it could be with more cooling.
Since you are pulling at long intervals up hill, I would expect your pan temp to rise from lower road speed not helping the cooler function as well.
From all that I have read and researched about this subject, I don't think many fully know how complex the total cooling gets in these systems.
You will see life expectancy charts versus temperature of operation but they never say where the temperatures are being measured.
The prime thing to be awhere of is the fluid breakdown point.
Syn fluids and blends will take higher temps before breakdown begins to occurs.
Many syn fluid will be good for close to 270* + before there is any concern for the transmission.
If a towing combo runs very hot, it is a good idea to change fluid at much shorter intervals.
Fluid breakdown causes solids to form, in combination with the clutch and band materials, begin to cause wear and surface slippage. Once this begins, it's to late to reverse the action. The linings take on a glaze that then accelerate slipping at an ever more rapid rate. Then there is the metal parts lubrication that also fails.
For others, i'm not trying to prove a specific point but to bring to the table more about this than I have ever found anywhere else, so far.
I got into this this deep in hopes it would be of interest to some others.
Good luck.

 

Bluegrass, interesting thread. I too was concerned about transmission temperature and decided to monitor closely. I bought the wrong truck(4.6 with tow package) to pull my 4,000 lbs travel trailer, but have managed to do quite well with it by using temperature guages and coolers.

After finding this forum several years ago and reading the large amount of information available I began to be concerned about burning up my transmission.

My first action was to install a temperature guage in the output line from the torque converter. I saw temperatures in the 240* range from time to time on hot days and slow traffic. I installed a 22,000 lb cooler on it, and saw temperatures drop by 20* to 40* on similar ambient temperature days.

I then installed a second temperature guage at the output of the factory installed transmission cooler, last in line before going back to pan, and saw temperature differentials that vary from -10* to about 30*. The -ive differential is attributed to the radiator warming the fluid during time of minimum fluid heating in the torque converter.

Your data makes an interesting point about fluid being heated up again in the pan. I also change my fluid annually, well before the recommended interval, but I consider it cheap insurance.

Thanks for sharing the information.

 

When I towed my trailer this weekend it was cooler on Friday going out and hit a little rain. It was in the low 60's I'd say. My temps (sensor on the trans out line and totally stock setup) stayed at around 165* On some hills when I was in second and before the trans locked, it did get to 180*, but once locked, it went back to 165*.

On the way home, it was warmer... (that's the way it always goes of course!!) It was in the mid 70's. My temp stayed closer to 180*, but it would go down to just above the 165* mark while the trans was locked. I did get it to 195* on one slow, winding hill while the trans was in unlocked second..... No big deal, and once the TC locked, it went back down to 180* and once back on the flat and in third, went back below 180*.

The only time it went above 195* on this trip was about a 1/2 mile from home! Having to go thru several stop lights and it just having run for over 2.5 hours seems to get the heat up when it has no air flow.

Once I got home, my routine is to park in front of the house and I let the engine idle in netural while I take off the WD bars and such before parking the beast. By this time, the temp has dropped to 180* (from it's 195* + mark). Once I get the trailer lined up (I have to make a sharp "S" turn backing the thing up an inclined gravel driveway) I put the truck in 4lo and the temp never rises above that 180* mark. Before I started using 4lo, it would go to 210* in an instant!

I also see the same basic temps when it gets to be over 90* outside too. So it seems my temps stay on the cooler side when it's < 70* outside and go to the 180* range when it's above 70* and stay consistant even when it's over 90*.

Just my experience with it... Oh, my trailer weighs around #4500 all loaded up and ready to roll....

Mitch

 

Thanks guys for posting you observations. I would say your all seeing essentially the same thing going on.
I to saw the action at times of fast temp swings when I had the radiator in the loop and attributed it to the engine thermostat opening and closeing as it changes the coolant temp in the radiator.
This is another element in the whole system that adds to the complex operation of temperature changes versus loading, time and outside temperatures.
I suppose that the one remaing way to cool the pan further is to use a pan with better heat loss ability and maybe higher capacity.
Two things to add for others are that for winter trans operation with a lot of cooling will cause the trans to take longer to heat to good operating temp and may cause stiff shifting until that point is reached and not to run in cold weather without the radiator in the loop. I have seup flared fittings and hose so I can switch things around after the towing is done.
Also there is always the question of gauge accuraccy. It pays to at least check the gauge reading in a pan of boiling water to see what you have.
Water boils at 212* providing your at sea level and the baro. pressure is close to 29.9. So the gauge shoud be within at least 3 to 5 * not 10 or 20* as I have found some to be.

 

I think my hotter weather temps stay in check better due to the routing thru the rad.... While I will still get output temps to 210*, I've not seen it any hotter and it's only gotten this hot when the TC is unlocked or in reverse or no air flow situations.

Dunno... Whatever works best for your particular setup and situation I say..... No two setups are going to be the same or in the same situations IMO...

Blue, since you have been taking temp readings from many different points with sensors and a heat gun and are satisfied with your results, I'd say that you have a decent setup..... I've not gone that far, but taking the temp where I do and knowing that it's unlikely that my pan temps are higher then my output temps anyway, it gives me enough info to tell what the trans is doing. I also have a "real" water temp gauge and between the two, I get enough info to determine if I'm working the truck too hard.

I have the trans serviced every year (20k miles) and it's always very clean and pink in color (or red, depedning on what your interpretation of trans fluid color is!)

144k miles on the rig and going strong! (knock on wood... )

Mitch

 

I just finished a trip from Northern Maryland to Myrtle Beach SC and back. Total round trip milage 1010 Miles. I tow a 27 foot travel trailer weighing in around 6000 lbs. I tow with a 2000 Expedition w/ 5.4L and 4.10 gears. I had a similar question with my transmission. I installed a B&M Trans temp guage and a Trans-Cool aux. trans cooler in place of my tow package stock cooler. My trans temps were about 180-190 degrees on the interstate doing about 65 MPH. It never really went any higher. I have my sensor installed in the transmission pan also.

Before our trip I had our local transmission shop check the installation and they measured the actual trans. temperature through their diagnostic tool hooked up to the diagnostic port. They told me my guage was running about 10 degrees hotter than the internal temperature sensor. The trans shop says that I was actually reading the pan temperature and not necessarily the fluid temps. That made sense to me because I noticed that when I stopped to eat on our trip, after about 45 minutes rest, the trans temp guage would read about 20 degrees cooler than when I stopped. Could the fluid cool down that quick?

Just my experience..... oh, By the way, I run synthetic mercon fluid in my transmission and I replace it about every two years.

Jeff

 

I'm close to being satisifed but will be making two more changes.
Put the coolers in parellel and add a 6 inch fan to the assembly then call it quits because there is not much more to do and I have a good handle/feel for the whole thing.
I was looking at a custom big tow rig at a dealer today and noticed it had a trans temp gauge. It was marked yellow in the 240 to 260 range and red above that to 300. No way of knowing if that is pan temp or some other location.
On the pan reading location, it is a small problem measuring the temp if the sensor and the fitting in the pan are all metal and read the metal pan temp as well as the fluid temp so you have to take the results as close enough save for gauge accuracy. Same goes for a pressure port location and trans case temperature.
For outlet inline locations, the whole sensor block attains essentially the temp of the fluid passing thru minus and convection/radiation cooling from moving airflow under the truck.
At the radiator line sensor location, your somwhere in between the extremes of trans outlet temp and what come back to the pan. At this point I would feel that you would not know how high is to high considering the outlet temp and what is going back to the pan because you have to many points that cause temp change along the way.
I think we about put this to bed and should provide a good feel for what to do and expect.
Thanks again.