TH400 Slipping When Warm - Chunks in Oil Pan

My truck's TH400 2wd transmission leaks when parked and slips after it's warm. I replaced the vacuum modulator, pan gasket, and filter less than a year ago. I found what appears to be plastic chunks in the oil pan and some fine metal debris. Governor gear is fine. Thoughts? Am I looking at a rebuild?

Thanks.

82sierradude said:

My truck's TH400 2wd transmission leaks when parked and slips after it's warm. I replaced the vacuum modulator, pan gasket, and filter less than a year ago. I found what appears to be plastic chunks in the oil pan and some fine metal debris. Governor gear is fine. Thoughts? Am I looking at a rebuild?

Thanks.

Click to expand...

Yank it out and overhaul it! Debris like that in the pan = rebuild 100% of the time.

check out my TH400 Information Thread for video tutorials, parts lists, tips/pointers and additional resources to help you with the overhaul.

Ouch! Take Nicks' advice.

@82sierradude you knew the answer before you made this post…

nvrenuf said:

@82sierradude you knew the answer before you made this post…

Click to expand...

I suspected that a rebuild was in order, but I wanted to exhaust all possibilities before proceeding. The ATSG manual just arrived today.

NickTransmissions said:

Yank it out and overhaul it! Debris like that in the pan = rebuild 100% of the time.

check out my TH400 Information Thread for video tutorials, parts lists, tips/pointers and additional resources to help you with the overhaul.

Click to expand...

Thanks. Any idea which part may have shredded into pieces and ended up in the pan?

82sierradude said:

Thanks. Any idea which part may have shredded into pieces and ended up in the pan?

Click to expand...

they dont look metal, so my guess is its friction material

82sierradude said:

Thanks. Any idea which part may have shredded into pieces and ended up in the pan?

Click to expand...

You're welcome. Looks like a combination of bronze thrust washer which sits on the front side of the rear planet and front/rear planetary teeth but hard to tell from the pictures...Let us know what happened when you open it up...Also, gear train failure (if that is what it turns out to be) in an otherwise stock to mild-use vehicle points to a restriction somewhere in your system...Once you have the trans out, extensively flush your cooler lines, internal transmission cooler and external cooler to ensure all that debris is removed...If you cannot get the cooler(s) clear after numerous attempts, either have the radiator/cooler rebuilt or replace the radiator.