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ive got an 86 chevy pickup, and when i went to leave this morning it was like all gears were nutral. when i got out i noticed why, there was a red river gushing out from somewhere in the bell housing/front of trans. now i am not a transmission guy, but somewhat of a mechanic. i pulled the trans out expecting to see a crack or some blatant reason why all of my fluid just got regurgitated, but things appear normal. had the trans rebuilt about two years ago when i put a new motor in so the front seal still appeared to be in good shape as well. any insight to my problem would be greatly appreciated. - J Ryan  

the front seal could have broken... there is some pressure behind it...

since you have the converter out.. can you look through the gap and see if the bushing is in place about 1/2 to 3/4 inch back from the front lip of the seal..  somebody will post a better measurement i hope...

when the front pump bushings slide forward..  it can distort the seal and cause  leak like you describe..
please.. don't try to pull the front pump without knowing what to remove from the pan side to free it ..

the torque converter could have a crack in the snout..

while you have the transmission out..

can you blow compressed air through the transmission cooler lines...   blocked lines will cause problems that will pump the fluid out of the filler tube and vent..

there is also the filler tube..  was it properly bolted to the back of the block.. if they are NOT bolted to the back of the engine tightly.. they can wobble where the tube is narrowed for the oring to fit and leak like crazy..

there is also a Kick down cable there that can leak.. crack and leak..  separate  and leak...  

oh... 86 chevy trucks probably have a 700R4 transmission.. not a TH350...



pan 3 fits TH250, TH250C, TH350, TH350C, TH375B 13 pan bolts..

pan 6 fits TH700-4R, 4L60, 4L60E 16 pan bolts  

.  

its definitely a 350 trans. everything that was described seems good. certainly seems to have been coming from the front seal, but the seal looks good. just beyond the front seal inside there does seem to be a little ring or something thats loose.  

oh, wait. i was trying to remember from last night. the loose ring thing is actually in the converter not in the trans.  

Is the convertor neck scored or scratched at all? Did it leak while cold or only when hot? Is this a leak that progressively got worse or did it happen suddenly?  

well there was a slow leak that had very slowly been getting worse over the past 4 years, got to a point when i had to add about a quart every two weeks. but this day it was just like all hell broke loose and it dumped like multipple quarts out all at once either when i started it, or when i put it in gear. i dont see any unusual scoring, or scratches.  

Is it possible that the original leak was a small leak from a pump bolt or the pump o-ring and this new heavy leak is a cooling line that was rubbing on the case and ruptured right by the bell housing or just rotted out? If the fluid was pouring out of the front seal you would see something damaged.