I have a Bulley Dog Outlook moniter. It dispalys the reading that the ECU gets. The stock trans temp sender is in the pan. It's part of the module with the pressure governer. The module is non-servicable, and all gets replaced as a unit.

Driving around empty trans temp never gets much above 90*. Towing (light) across KS last summer I had the cruyise set on 68. Even with the steady climb west out of Colby, trans temps never got above 115*.

Thinking the sender was malfunctioning, I had it replaced. It's essentially the same readings.

I figured that was just how it was supposed. But then I was reading some other stuff, and maybe it's not. Does that sound right for a pan temp?

This summer I think I'll buy a laser thermometer and see what the pan temp is.

 

Forget the pan temp. Monitor the front feeder line(feed line to the cooler) for an earlier warning of high tranny temps. Pan fluid has already been cooled.

 

I have a 5.9 and the trans temp is read at the pressure test port on the side of the trans with an Autometer gauge. When the cold weather cover is closed the trans hits 150 and stays there because the engine coolant to trans fluid cooler takes over. In the warmer temps, the trans temp hits about 130 and slowly increses with a light load (me in the truck). Never seen trans temp over 190 when towing 9,000 lbs thru mountains in PA.

The 5.9L diesel models equipped with an automatic transmission are equipped with a water-to-oil cooler and a separate air-to-oil cooler. Both coolers are supplied as standard equipment on diesel engine powered models when equipped with an automatic transmission.

The water-to-oil transmission oil cooler is mounted to a bracket on the intake side of the engine .
The transmission oil is routed through the oil-to coolant cooler first, then to the air-to-oil cooler where additional heat is removed from the transmission oil before returning to the transmission. The auxiliary air-to-oil cooler has an internal thermostat that controls fluid flow through the cooler. When the transmission fluid is cold (less then operating temperature), the fluid is routed through the cooler bypass. When the transmission fluid reaches operating temperatures and above, the thermostat closes off the bypass allowing fluid flow through the cooler. The thermostat is serviceable.

The 6.7L model diesel with automatic transmission is equipped with an air-to-oil cooler only. This cooler is located in front of the radiator .

 

OK, it's been that way since I bought it. So I guess that's a normal condition for the pan fluid. The ECM moniters that temp, so the engineers must (I hope?) know what they're doing. I won't worry about it anymore.

 

When you find that elusive little bugger you post a pic.


Pan temp generally runs 40-50 degrees less than coolant temp when up to temperature. So 130-140 is normal in steady lockup mode as measured by an analog gauge in the pan. Non-lockup just varies depending on a lot of things.

The electronic gauages jsut never seem to agree with an analog gauge on most of the parameters.

 

The parts of the t/stat.
#2 is the t/stat.

 

Thank you, that is what I was looking for.

 

Anyone have a part number or source for a replacement on this transmission oil cooler internal thermostat?

My local dealer says they can't get the component separate from the entire air-oil cooler unit.

I'm pretty sure mine has failed in the "bypass" position, as my transmission temp readings have recently started to match, almost exactly, my engine temperature (i.e., running at about 195 - 200) under normal highway driving conditions. Randomly, the temperature will drop rapidly back to what was previously a normal range .. low 180's, then slowly climb back up again. Dealer can find nothing wrong with the transmission, and it feels like it's operating normally, which is what is leading me to suspect this internal thermostat and the bypass.

Any other suggestions would be greatly appreciated!

('05 3500 5.9L auto 4x4 - 110K miles)

Sincerely,
Mark

 

You guys are full of good info today. Mine has been matchin water temp lately as well. Never knew a thermostat was in the tranny cooler up front.

Will be changing the Torque Converter next week along with the solinoids in the valve body. It will be interesting to see after the change out if the tranny temp stays with the water temp.

Hope some one has a part number.

EDIT> Just called the local dodge dealer and talked with parts. They confirmed it is servicable, but have no part number. They will call
dodge and see what's up. Will post findings.

 

is that picture the checkball?

 

NO! The first pic is the exploded view of the t/stat. the second pic is the location of the t/stat in the air to oil cooler.

 

I was called back this morning by the Dodge Dealer Parts guy about the Thermostat for the air to oil cooler. He said Chysler says you have to buy the entire cooler. The cummins guy at the Dodge Dealer said he had serviced this part in the past. The parts guy does not understand whats going on. He going to keep pressing to find out why the thermostat can't be purchased.

I guess this thing could also act like a orifice tube for the A/C and jam up with debries from the tranny.

 

That's the same response I got from my dealer.. buy the entire air-oil cooler in order to fix/replace a serviceable part... sigh!

Please let me know if you can find out anything more.

- Mark

 

Yes it can. Pull it out and clean it up. Thats worked for several people.

 

Is it possible to remove the thermostat without losing any fluid or removing the intercooler?