Hello All

This trans has got me confused...seems like a different problem than most folks get. I'm having trouble with no auto downshifts when slowing, but ONLY when the trans is very hot.

My rig is a Class B motorhome of about 9000 pounds, made from a 98 Dodge Ram B3500 Van, 360, 46RE, 60,000 miles.

25,000 miles ago, I put a Trans-Go TFOD Diesel shift kit in it to fix the TCC slippage, with new overdrive solenoids and new governor pressure solenoid and governor pressure sensor.

Over the past 2 years and 20,000 miles, we've done mostly flat vacations, and the fluid stayed nice, and it always shifted correctly, up, down, torque converter locked at the right times, etc.

This past summer, we went to the mountains of Colorado, and with all the slow climbing in 1st and 2nd gear (10-25 mph), the fluid started taking on a darker color. Not burned, but not pink like it used to be.

After 2 weeks of climbing all day long, we were in a flat area, in traffic, and it started taking off in high gear. Usually on slowing, it downshifts 3-2 at about 12 mph, and 2-1 at about 8 mph. In the heat and traffic, it wouldn't downshift by itself. I could always manually downshift it, but that sure gets old.

We got home, and I changed the governor pressure solenoid and governor pressure sensor, drained about 9 quarts of fluid, and installed a Mag-Hytek standard depth pan and new filter. I also removed the check ball from the line going to the radiator. It also has a factory external trans cooler between the A/C condensor and the radiator. Flow through the lines is very good...I removed the rear return line, and got a very good spray of fluid on startup.

The problem remains...when it's cold, everything works great. We live in the hills east of San Diego, and after climbing for about 10 minutes at 10 mph, the trans doesn't want to auto downshift while slowing. I got it back to the house, and the pan sure seemed very hot. Once it cooled off, it was back to normal. There are no codes or warning lights.

I am unable to access the transmission's internal temp reading, using Torque Pro through the OBDII port. (Anyone know how to do that??) But, judging on how the fluid changed, and how dang hot the pan was to the touch, my bet is that the fluid is overheating from overloading and insufficient airflow through the external cooler.

I'm planning to bypass the radiator, and install an external cooler with its own fan and thermostat, because the engine is seeing 220-230 degrees during these slow climbs, which is more than what the trans fluid should ever be.

Is not downshifting 3-2 and 2-1 a normal "feature" when the fluid overheats?

Thanks,

Gerard

 

Well have no idea what is causing the no downshift, though I can say with aftermarket coolers I have always noticed a drop in summer time engine temperature after the install. I run Hayden coolers on my vans never had a problem simply no complaints and again my summer engine temp run ~15 degrees lower and of course my trannys are running cooler as well.

Seems you may need to speak to a person with expertise in high performance/Hd trannys. Good luck and happy holidays.