dieselfitter

Really thought that taking the transmission to Mack would be a quick easy solution. In most cases I would have just put a reman in but couldn't find one. Talking with Mack, they made it sound like an easy fix. We are a fairly large and busy shop here in the mountains of Colorado so I try to out source transmissions and differentials. Like I had said before, there are not a lot of Macks around here or the information to work on them. We have Mitchell 1, but not very helpful in a lot of areas concerning Mack trucks. Out of the 100 or so trucks that we maintain I think we have 3 Macks. I put an injection pump on and E7 350 here awhile back and added that to my "Never again!" list... I did order a case of transmission air filters for the customer. I'm confident that the failure of this transmission was due to sticky cylinders and gummed up inversion valves. Installed all new airlines on tranny, replaced regulator and rebuilt inversion valves. Filled transmission with synthetic 50wt.

Seems like the industry lost a lot of good educated people all at once. Talking with the younger guys at the dealerships, they all knew of someone with the information that either retired or passed away within the past few years and the information was never passed on in the shop. Mack made some really cool stuff, just not a lot of it! With all of the new equipment and changes being made it is almost impossible to find the information unless you have access to one of the old timers that is willing to give you a minute or two.

Finally! Pulled the top cover off and sure enough the shift dog was not in the fork hole. Used a mirror to look under the cover as I put it back on. Hooked all of the airlines back up and put it in reverse. Backed out of the shop, went forward about 20' and tried to go back in reverse. No GO! Just grinding.. Cycled the shifter through the positions and it was stuck in forward when I put it back to reverse. Pulled the cover back off and left the air hooked up and cycled it back and forth again. The reverse shaft was barely moving back and forth. Pulled the cylinders apart and they were full of gunk. I had given Mack the seal kit and asked that the shifter be rebuilt as well. Nothing was touched. Cleaned it up and put it back together. Works like a charm! The truck has an air dryer and a filter. Filter doesn't look like it had ever been changed. The lesson learned here is that I assumed that the shop would repair and assemble the transmission correctly. None of the tranny shops that we do business with would touch it because they had no information on it. Reluctantly I took the trans. to a Mack dealer. Paid a ton of money and still ended up having a mess. Don't work on or have a lot of Macks in our area. After reading some of the information that you guys have put on the forum, I can tell you that if and when I have another problem I will be right back here. Thank you!!

According to the diagram, I have the inversion valve for reverse hooked up correctly! After dealing with 3 separate mack dealerships that is the 1st schem that I have seen with the supply, delivery and control for the inversion valve spelled out. There is still 1 more air shift on top of the trans. for the low gear reduction that doesn't show up on any of the diagrams. It will show ports 5 and 6.

Referring to the low gear reduction that is activated by the switch on the dash. Ports 5 and 6. Has an inversion valve and not sure if I have it plumbed right. Seems to work, but would like to see the schem. to make sure.

Not stupid at all! Going to the shop in a few minutes to pull the top cover off and see what is going on. I was hoping that after a $4000.00 bill at the mack dealership for the tranny repair that would not be the problem. Last night I pulled the side cover off to peek up through the trans. I could see the shaft and the dog moving back and forth, but no gears moving. Couldn't see much through the hole, so now off comes the top. When I go through the pressure and exhaust graph that I have everything is as it should be. Ports 1-4 are on the diagram, but no 5-6 for the extended range. I am probably making this harder than it needs to be and get myself confused. If you have the schematic with the extended range, I would love to see it. Thank you,

Howdy All, I have a 1994 CL713 tandem. Pulled the trans. and sent it to the shop to repair 12th gear and a shift fork. When I got the trans back, all of the air lines and diversion valves were put nicely in a box with no labels. I have tried for weeks to find information on this transmission and have found nothing. We do a lot of business with the Mack dealership and they can find nothing either. I have reinstalled the transmission and have gotten all of the forward gears to work, but have no reverse. When I put it to (R) on the shift knob I get the same results as I get when I put it to (N) other than the shift piston is moving. I know that the shift shaft is moving back and forth because the indicator comes on and I have pulled the plug and watched it with a mirror. I'm not quite sure how to plumb the inversion valve into reverse (ports 3 and 4). Seems like I'm putting the trans. into neutral and doing nothing more than moving the (R) shift shaft back and forth. What else has to be engaged to make reverse work? Any help would be greatly appreciated. I am stumped!