AHHH! transmission is spilling its guts again!

[COBALT]

My TH400 has leaked since I got the truck over a year ago. Never really a lot of fluid, and sometimes none at all. You're doing the best you can do for a preliminary diagnostic: find a pattern with the leaks. Mine turned out to be parking the truck pointing downhill. Whenever that happened it would leave a puddle. I was also getting a TON of blow-back, so I realized it might be the front seal or converter.

Now that I've had the truck up on jacks at my dad's place for the past month it's left a HUGE puddle, which confirms my thoughts that the front seal is the culprit (we poured the shop floor to have a 1" drop out the front doors). Since pressure in the transmission hasn't been brought up with the engine running the fluid is free to find any hole it can find to run out of. Smart me wiped the pan, case, governor cover, tail extension, and inspection cover before I left it alone a few weeks ago. Now it's magic. The only place there's fluid evident is on the inspection cover (which covers the converter). Therefore, the leak is at the front seal or out of the converter itself!

Now this doesn't take into account what happens when pressure is built back up. Another leak may exist where its only evident when there's high pressure in the case. Therefore, I'll have to replace the front seal, and check for leaks again.

Sometimes you just have to be systematic and check one thing at a time until you zero in on the reason. What sucks is sometimes you have to park the truck and NOT drive it until you find the problem. Patience is a virtue.

Good luck.