Changed trans fluid in my TH400 and now it wants to slip and not get into gear.

[HeavyHauler]

Originally Posted by 57taskforce

Did you check the fluid with it level, running, and in park? I see you made mention of neutral but not park. I don’t think you’d loose forward and reverse both because of clean fluid, and definitely not right away on start up. I could see maybe after a few hundred miles of the clean fluid circulating thru the system but not immediately on start up. TH400’s are tough as nails. I bet it’s still low on fluid.

Yesterday I put your theory to the test and added 2 more quarts. It did nothing but at least I tried. Most likely it is overfilled now but it doesnt matter because I will be pulling it anyway this summer.