GUTTING THEDRAINBACK VALVE
2004 Dodge Ram 2500 HD 4x4
This install article is only for reference. Perform this modification at your own risk.
The drainback valve on many Dodge diesel trucks is located under the hood on the drivers side just behind
the radiator stack. Find the trans cooler lines coming out of the cooler up front and you will locate the valve attached to the cooling line about 12" back from the radiator. It's intent is to prevent fluid from draining back out of the torque converter when the truck is shut down. There is also a flow restrictor in this valve which I presume slows the flow of fluid through the front cooler so more heat can be drawn off.
The reason I gutted mine was because after installing a performance transmission and lower stall torque convertor, I was experiencing 30-50 deg higher transmission temperatures which caused my transmission to do strange things during the temperature spikes. It would begin upshifting into 3rd gear and lockup and immediately hit 4th and lockup at 30 mph at about 237 deg fluid temp as indicated by the sensor, read by a scan tool. Gutting the drainback valve increases fluid flow though the cooler at the same time it helps keep the fluid in the convertor moving through faster, not getting as hot (I presume). Although increasing flow through the cooler might have a negative impact on cooling, cycling the fluid faster through the convertor seems to have a greater cooling effect (again, my theory).
In my case, it dropped my trans temps over 15 degrees.
Using two 7/8" wrenches, disconnect the fittings. Almost no fluid will run out. You can then reposition the valve facing down
under the truck as it is on the rubber side of the lines. From under the truck I performed the following operations......
For those of you who are shaky about drilling this I advise you to get someone else who is a little more comfortable with
drilling brass. Brass is very difficult to drill when you are simply opening up an existing hole. It will grab the drill bit
agressively and pull the drill in. You must drill very slow and step up in size until the ball comes out. I started with a .337" dia.
drill and progressed as follows.... .364, .373, .403. The ball fell out at .403 and gave me a nice size hole. When you push in
on the ball with the drill bit, some fluid will drain so be prepared. Maybe a 1/4 cup at most.
Here is the ball after it fell out.
You then have to pull out the spring and the flow restrictor with needle nose pliers.
Closeup of the flow restrictor. It's bent up from pulling it out.
Here is the valve with everything removed.