edhunter

I changed the filters in my "new-to-me" 2007 4x4 dually. Picked it up this weekend, it's got 195k miles. Truck drove 250 miles home just fine... Changed all the fluids except the F/R differential today, saved the trans for last. Dropped the pan, swapped the two filters, then filled with 6-7 quarts of ATF+4. Thought I'd disconnect the cooler line and pump the new fluid through the system, but when I did this I got very little fluid coming out the cooler line. Truck was in neutral. Shut it down before I screwed something up, but not before I backed it back into the garage, which it did fine. Wondering if I've got something wrong, or was wondering if the pump bypasses the cooler until the fluid gets hot...
Can someone set me straight?
Thanks!

genesag

In neutral the trans will pump very little through the cooler. I use this method to "flush" the torque converter. Do just what you did, but set the e-brake and shift to drive. This will pump the fresh ATF from the Trans pan through the Converter and out the cooler line. It's good to have some help at this point so you can replenish the ATF as it is pumping out.

redruM Hauler

my .02
i would keep as much of the old fluid in the tranny as poossible, unless you have had it changed regularly, new fluid with new detergent cleans out things that are better left alone