allison problems

[tx dave]

Hey guys, here's a new one on me. My allison has blown fluid out of the top vent. I noticed a small puddle under the truck in am. I went to town to run around shopping and was going to check it out when I got home. I stopped to fill up and took a look under the truck and there was a whole bunch of fluid leaking. I ran it by a buddies trans shop hoisted and looked. It looked like it was coming from the vent. not real wet on top but a lot on the side where all the wires are. I brought it home, sprayed it with degreaser, washed it off and this morning I will start it and look again. But my question is what will cause it to blow fluid out the vent. I understand the allison is a very simple trans on the inside with a very good computer brain. what should I do???

[Jake99Z71]

What year is your truck? Are you running the TSB vented dip stick?
When checking the fluid is the trans at least 150*F and reading just on the bottom of the Hot Hash marks?

[tx dave]

The trucks an '01', 245K. I went ahead an dropped the pan yesterday. very clean, no metal. very little on the magnet. I changed the internal and spin on filters. filled withTS-295 synthetic. There were no leaks after I cleaned everything off. With fresh everything I'm hoping it was only a fluke but I'll see next time. For sure, I'll be glancing under the truck every time I stop from now on.

[hogbody]

My 2003 was venting tranny fluid after a long hard pull where the temp got warm. There was a TSB for a new tube and fluid level stick.......Solved the problem.