96 F250 newly rebuilt tranny has problems

[*rake*]

My truck had it's stock auto tranny rebuilt as a HD about 2 months ago. Today was the 1st time I took it out for a long drive on the freeway since the rebuild... after about 1 1/2 hrs it downshifted from OD to 3rd going up a hill, but then wouldn't come out of 3rd. When I exited the fwy & stopped it downshifted VERY abruptly with a loud bang & lurch at each shift. It smelled burnt, & the "OD off" lite on the column shifter was flashing. Every time I had to stop after that it was the same bang-bang-bang back down to 1st. I had no load at all on the truck for this trip. On the way home it still shifted really rough (not quite as bad though), but the flashing light stopped. It had a similar issue the day I got it back from the rebuild, but when I took it back to the guy who did the work for me he said there was a code that had to clear & it should be fine after turning it on & off a few times. This seemed to be the case until today. Any ideas on what may be going on with this tranny? Thanks!

[ModMech]

a '96 should have an E4OD (4R100). If the fluid is burned, then something is slipping excessively, could be the lock-up torque converter or a clutch pack. One of the most popular ways to get "HD" out of a rebuild is to INCORRECTLY increase the line pressure. This can, and will, burn up the trans oil and cause very harsh shifting. This trans is electronically controlled, so if there was anything really wrong with the EEC or sensors the CEL would also be on. Take it to AutoZone and get the codes read, that way your "rebuilder" won't be able to BS you.

[*rake*]

Thanks for the advice... I'm going to try & get my $$$$ back from the guy who f'ed it up in the 1st place. He's a friend of a friend... you know how that goes. Autozone wanted $190 for me to rent their diagnostic machine & do it myself, so I took it to a real tranny shop. They said the fluid smelled burnt- probably T/C, & the codes showed electrical probs in the tranny &/or its computer. Unbelievable... $1300 & 3 weeks & the 1st guy couldn't fix it right. I know he's going to say bring the truck back & he'll fix it, but at this point I don't trust him any further than I could throw an automatic tranny.

[97chevyman]

Before you put the horse in front the carriage here, check some things. Get those codes read, take it to autozone or a tranny shop. If it is the t/c lock slippage, take a look at the speedo sensor, is you speed working right? Because if the speed sensor is bad, the computer will detect t/c lock clutch slippage, and raise the line pressure, creating harsh shifts.

[*rake*]

Well, the new shop tore into my problem "rebuild" today & found that the cooler was never flushed or replaced when it was rebuilt. So, it plugged up, the thing overheated, got stuck in 3rd gear, got hotter, & fried its T/C. Who knows what else they'll find further into it. I'm taking all the burnt-up "new" parts back to the guy who made this mess in the 1st place. Talked to the guy who recommended this rebuilder & he said he'll stand behind me & help get my $$$$ back. I'm so mad I could just shove a drive axle up this rebuilder's....*deep breath*... oh, nevermind.