Engine/Transmission (1998.5 - 2002) auto trans temps with 3.54

[ablum]

Just like a good DTD owner, I have placed a transmission oil temp guage on my pillar(Geno's dip stick sensor). I was also advised to run in 3rd when pulling my 14ft gooseneck dump trailer with a load(16 to 18,000 GCWR). However, I seem to get lower temps when I leave it in overdrive. Floats between 160 and 200, depending on stop and go. Usually don't get to 200 unless I am backing up. Does anyone have any numbers for me. Is there something I don't know about when I am using OD? I have plans to switch over to amsoil. From reading past issues there was some concern about amsoil being too slick for auto's, any updates? Thank You

 

[rweis]

There are a few MILES of threads about transmission temps. There are a few more miles of transmission wars. Check the sticky thread about not doing transmission wars.



Each one to their own opinion, but I tow in 3rd O/D out to keep transmission pump pressures up. I think that about 1600 rpm empty and 1800 rpm pulling is min rpm to keep transmission from slipping.



There are a lot of variables, flatness of the terrain, wind load on the trailer, weather temps, cross winds etc.



The hottest place to measure temps is in the line going to the water heat exchanger. Tons of threads on that too. Pan temps have a whole different set of parameters.



I would recommend a tall cool one and a couple of hours and search.



Bob Weis



Going in for a XXX rebuild 3 Aug, can't wait

 

[Cummins4Life]

I have a regular deep MagHytec with the sender in the pan. I see 125-150 on the highway. Stays around 150 in town in stop and go. I've seen as high as 200 on the dyno and a lil higher when in 4hi in the mud or snow. I've never towed anything with any weight so cant help there. I havent noticed a difference between 3rd and OD, but lockup sure makes it cool off fast.

 

[JBlock]

Never above 140 except

My probe in the mag-tech double deep pan.



I have only seen the guage move off the bottom mark of 140 three times.



Crossing the Canadian border, idling for hour one crossing, once returning.



the third time, backing up the car hauler with my 42 packard, grossing 9000 pounds.





JB

 

[klaybus]

Auto Trans Temps

I run just over 100 with 3. 54s. I also run in 3rd with it out of OD unless on freeway. Temps in 3rd lockup or OD lockup are just over 100 degrees but will quickly go to 180-200 in stop & go traffic.

I have my temperature sending unit on the line coming off the torque converter going to the heat exchanger where the transmission GOD says to put it. ($100 line from DC parts counter)

I can quickly get the temperature up to 220 while baking my trailer (#6000) into my driveway to put away... ... I typically shut it off as fast as I can when the temps get over 200 degrees because it tends to cool down faster when shut off vs putting it in neutral & letting the pump run FWIW... ...



Clay

 

[rrowdy]

I usually tow in 3rd at about 2150-2250 rpm but on long flats I

sometimes put it in OD. Running in 3rd and at the higher RPM's also drops the EGT some.



I recently installed a DD pan when I serviced the transmission

and after doing a search on the subject, I decided it would be best to install the sensor in the line going to the primary cooler so the temperatures leaving the TC could be read more accurately.



Out of lockup it climbs rapidly and within a few minutes can be as high as 280 degrees but once in lockup it rapidly settles down to about the 160-180 range. If I towed 16-18K like you do I think I would stay in 3rd



rweis gave you some good advise, check the archives, read as much as you need and make your decision based on what you have learned.

 

[Huff N Puff]

The trans will run cooler in OD and lockup

Because the lockup in the converter, by passes the fluid coupler in the converter where most the heat in the trans is created.

 

[MacGreenie]

XMSN Test Ports Temperatures

I have a Westach dual temp guage with one 1/8 NPT probe stuffed into a test port on the passenger side all the way aft on my 47RE. The temp split between that and the DD pan sender is about 30 degrees.



Driving unloaded on a hot day (90) and stop and go the transmission sender gets up to 180 and the DD pan to 150 or 155. Cools down once on the highway, though.



There are three ports on the transmission (3 right side and one left side) that are plugged with 1/8 NPT plugs. They seem to take a temp sender unit with no problem. I wanted to avoid buying a new line with an inline sender port so I went this route.



I assume I am measuring the fluid temp in the transmission where it is doing most of the work... sort of like sampling the fluid temp as it leaves to go to the cooler.



I know pan temps are slow to reveal "thermal runaway" conditions.



Thoughts anyone? Is there a better port I should be using for temp sensing?

 

[keimmmo]

MacGreenie,



I couldn't see paying $100 for a trans line either. I plumbed in a 1/2 inch pipe T in the last curve below the cooler on the side of the motor. I used compression fittings on the line and faced the T so the fluid coming out of the line hits the sender and goes up to the cooler. Seems to work fine and everything cost well under $10.



Concerning that "cooler" on the motor... if the thermostat in the motor is 190 degrees, anything below that on the trans temp gauge makes it a transmission HEATER!!! I want to install a 180 thermostat in mine!!! I pull a lot of twisty mountain roads where I can not get above 25 mph. With a 10,000 pound travel trailer, I have a hard time keeping the trans temps below 220 degrees!!!



I also have noticed I build heat down shifting and engine braking as fast as or even faster than pulling in the lower gears. I haven't heard that mentioned before though. Any comments? Third and fourth lockup always run nice and cool.



Steve