2004 Dodge Diesel auto transmission

I owned a 2006 Ram 2500 CTD with the 5.9 auto and even though I took care of Transmission religiously it went at 132,000. Read on numerous Dodge Cummins sites that the 48Re Transmission only lasts around 150,000. Ended up trading truck in on new dually but engine was great.

I would suggest removing the ball check valve mentioned previously. It greatly restricts the flow of trans fluid, even if there isn't clutch debris stuck around it. I watched an entire rebuild of a 48RE (third gen Ram auto trans) valve body on utube, and at the end, the professional rebuilder mentioned the ball check valve, and said he has seen debris getting stuck around that check ball, burn up transmissions. Then he said, "Get it out of there!" I did.

It's inside the top of two transmission fluid lines, behind the driver's side wheel well. You remove the hose with a quick release tool, drill out the check ball, clean the hose, and re-install. The hose is only about 8" long. The check ball is there so that when you shut down the engine, the trans fluid doesn't drain out of the torque converter. This, so you can start the engine and drive away immediately. With it removed, after I start the truck, I put the trans in neutral for 15 seconds or more before driving away, so the pump refills the torque converter.

I also pulled the thermostat out of the OEM transmission cooler (also mentioned by previous poster), and reversed it so the cooler is never bypassed. I had found that my thermostat was stuck in the bypass position, and the trans fluid was NEVER getting circulated through the transmission cooler!

I would suggest that transmission temperatures be monitored in some way. You can pull it off the ECM with an CTS Edge Insight gauge (what I did). There are other digital gauges that plug into the OBD2 port. I used the ScanGauge II to pull trans fluid (plus anything else on the ECM, like coolant temp) off a previous vehicle. Some people use the Torque app.

With those fluid changes, the bands should be getting adjusted as well. One is accessible externally, the other requires removal of the transmission pan (while the transmission filter is being replaced). When the front band runs out of threads during adjustment, it is worn out and needs to be replaced soon.

A common problem is a shuttle shift between 1-2 during light throttle applications. The fix is to replace the pressure transducer, and while at it go ahead and replace the 'whateveritscalled' solenoid. There is an upgrade by using using the GM solenoid in place of the factory spec unit.

A shift kit (TransGo or other manufacturer) will help with longevity of the transmission. They require valve body removal for installation. Quicker TC lockups, increased line pressure for better clutch application, without break-neck shifts. I have the TransGo kit in mine (without drilling the faster TC lockup holes) to help me with a 2-3 shuttle I had, which it resolved.

Torque Converter failure with the sprag when it tries to 'drive through' the brakes while stopping and high idle while in gear. The TC clutch doesn't fully release, kind of like pushing the clutch pedal about half way in, the engine is loaded so the computer increases fuel to maintain a set idle speed, so the truck 'power-brakes' when you aren't touching the throttle.

Consistent excessive heat could be a plugged/stuck thermostat in the transmission cooler. Pull and clean, and many people in warmer climates flip the thermostat around and install so that the fluid is always flowing through the fins instead of bypassing.

The ball check valve for the fluid cooler can become plugged and cause high temperatures as well. Or it can get stuck open and allow drain-back to the transmission and will cause a truck that wont move for a few seconds until it refills the cooling system and builds pressure.

Other 'signs' of failing don't normally exist. Not shifting into 4th, no TC lockup, getting stuck in 2nd, not upshifting, will usually suddenly happen without notice.

Remember that fluid is not circulated in Park. If you are nursing a hot transmission, idle the truck in Neutral so that fluid is circulated through the cooling system. Idling it Park for extended periods will generate heat in the trans.

I have the same truck with 188K on it now. I still tow long distances with it and use it as a DD. My trans started slipping at 155K in first gear in '13. I had it rebuilt by a local shop. They used HD parts and I have no complaints. I have no engine mods nor have I had to do any other work to it. It is still in stock form.