So Ive been looking at a truck my little brother's friend owns, it's a 2000 with a "built" 47re, and according to him he recently blew the transmission, but the tranny isn't that old and he said, "It will not go forward, it will sometimes but only to 25mph and reverse works." To me this doesnt sound blown but correct me if I'm wrong. I'm not versed in automatic transmissions so I'm in the dark here and anything helps. Thanks!

Try dropping the pan and changing the filter and fluid? It could be plugged filter. Transmission needs hydraulic pressure to operate bands and such. If the filter is plugged it can't pump fuild.

24 minutes ago, Mopar1973Man said:

Try dropping the pan and changing the filter and fluid? It could be plugged filter. Transmission needs hydraulic pressure to operate bands and such. If the filter is plugged it can't pump fuild.

If/ when I get it it'll be the first thing I will do to it. He said it started "slipping" but honestly I don't know his definition of slipping cause he was driving it daily till last Saturday when it finally started doing what its doing now, which leads me to believe all thats wrong is its clogged like you said.

Buy it adjust bands new filter and fluid and if it’s done swapin a 5 speed... 

 

This article should cover everything. But I would first try following the "Shorthand Diagnostics" first. Either way I suspect your dropping the valve body.

 

21 hours ago, TheGreatWhite said:

If/ when I get it it'll be the first thing I will do to it. He said it started "slipping" but honestly I don't know his definition of slipping cause he was driving it daily till last Saturday when it finally started doing what its doing now, which leads me to believe all thats wrong is its clogged like you said.

 

Slipping or starting in 2nd or 3rd? You need to get out a line pressure gauge and test at the accumulator. 

This article I wrote below is good for finding the accumulator port, you'll need it to get your line pressures. And there's actually 5 test ports on the transmission and you'll need to test all of them to see what your pressures are at and at which ports have pressure. I'm suspecting a valve body issue or you smoked a clutch pack. I didn't talk about all 5, but I should write one up.

 

 

Edited December 7, 20186 yr by pepsi71ocean