FFGomer

your torque convertor is locked, most likely cause is the kickdown pin has been removed.....

on the drivers side rear of of the transmission pan right behind the shifter input shaft is either an air cylinder (if it has an air throttle) or cable kick down connected to the transmission. this is held in by a single bolt and a metal clip. pull the bolt and clip then twist and pull the kick down mechanism out. their should be a small "pin" behind the mechanism make sure it is in there. might also be the govenor sticking (but I doubt it) if it is something to do with the govenor.near the rear of the transmission on the driverside is a 4 bolt square cover pull it off and pull out the govenor mechanism. make sure the spool inside moves freely along with the flyweights.reassemble and try it again. Good Luck!!

I'll take a look at that pin, but we have never messed with the transmission so I don't know how the pin would have been removed. I'll also check that governor. Thanks for your help.

Welcome to BMT! I fixed your thread title!

Glad to have you aboard!

Thanks for fixing that Barry. So far this seems like a nice bunch. I'm looking forward to picking some of your brains for information.

And the reason for the name of your initial post would be?

Rob

Sorry, I meant to type "Hello". Guess I forgot a letter.

We have a 1986 DM with an automatic transmission in it. The truck has been sitting outside for almost two years without running. The boss recently decided he wants to get it on the road and after replacing the batteries and getting her running again the tranny is locked up. As soon as I put the truck into Drive the motor stalls. Any idea what could be the problem? I'm hoping that there might be a fairly simple solution for this but if not, that brings me to my next question. How hard would it be to swap this tranny out for a manual one? And where would be a good place to buy a new transmission. I apologize, I don't know a whole lot about the different transmissions that Mack has put on their trucks over the years.

My name is Chris and I work for a towing company in Harford County Maryland. A few years ago we aquired a 1986 Mack DM single axle chassis with a Weldbuilt wrecker body on it from New York City and now my boss wants to get it on the road. So, I figured I would check out this site and hopefully get some answers to questions that might come up while we are getting the truck back together. Thanks in advance for any help ya'll provide.