I've found several threads about TH400 leaks and I'd like to consolidate the information regarding the different leak locations and the known good parts that everyone has used to correct them. If you have a certain thread that comes to mind, please link it. I guess the usual leak locations would be the pan, the vacuum modulator, and the speedometer gear housing.
Don't forget the shift shaft, the dipstick, the electrical connector, and the input & output seals. Bruce Roe
Add to the list that one pesky mud wasp who who likes to make a home in the vent tube, causing some serious "burping" of fluid up and out of the dipstick tube. Actually, anything causing the vent to be blocked will result in the same. Devon
Here's a video where I replaced the speedometer driven gear and housing seals. https://youtu.be/BpEO1sHLp7Q Sent from my iPhone using Tapatalk
That's a good way to warp the pan rail and make it leak for sure. Next to valve covers, the transmission pan is most vulnerable to over tightening.
I have no experience of putting stripes on bolts however I have marked them on multi step torque to yield applications to keep track. If one is unsure of the threshold of a bolt stripping you can always wind it till it starts letting go then back off a quarter turn. Then again I get a kick out of bending the minds of young apprentices to get them thinking for themselves
I know the proper way is to ball ping hamer with round side and use another hammer to bang the holes outward slightly, make sure the lip of pan is straight all way around, tighten them all snug and then a quarter to a half turn. If you are using a cork gasget you dont want to see the gasget squeeze out alot, just slightly.
Here's part 2 with the pan install using the Trick Flow TFS-1001 pan and Moroso 93103 gasket. Link: http://bit.ly/2eU3Jkj
