Popular Post South of Heaven Posted Tuesday at 05:29 AM Popular Post Share Posted Tuesday at 05:29 AM (edited) Good morning gentlemen. I'm Jason , I own a small trucking company and just bought a 1991 Mack MH 600 cabover to add to my fleet. It's got the 350 Cummins small cam with an 8 speed manual tranny. I'm really excited! My mechanic is going through everything now. He just did the PM , all fresh oil in the differentials and new wheel seals , bearings and shoes on the drives. Next hes gonna tackle an exhaust leak. He also fixed all the lights and fixed the wiper fluid pump that wasn't working. The AC is not working but we don't have time to dig into that right now. Ok, now the fun stuff.... The cab lifter isn't working. He removed all the hydraulic lines and had the drivers side Piston rebuilt because it was leaking badly. That was a hassle... But after that the cab still won't lift. Hes removing the pump now and is taking it the same hydraulic guy. He thinks that needs a rebuild too and and maybe the check valve inside is bad. Anyone have any experience with this??? I really wanna get this cab up because he doesn't wanna put the new fuel filters and then not be able to prime it. TY Jason Edited Tuesday at 05:32 AM by South of Heaven 9 Quote Link to comment Share on other sites More sharing options...
cruiseliner64 Posted Tuesday at 09:41 AM Share Posted Tuesday at 09:41 AM Cool truck Jason,we bought a Cruiseliner a few weeks ago and couldnt get the cab to jack up.it turned out to be the hydraulic cab lock seals at the back of the cab.the seals were gone and the system would not build enough pressure to release the locks and let the cab raise.dont know if the MH has the same set up but that was our experence.the truck looks really great. Paul 1 Quote Link to comment Share on other sites More sharing options...
BottleHauler84 Posted yesterday at 01:50 PM Share Posted yesterday at 01:50 PM (edited) On 9/3/2024 at 1:29 AM, South of Heaven said: Good morning gentlemen. I'm Jason , I own a small trucking company and just bought a 1991 Mack MH 600 cabover to add to my fleet. It's got the 350 Cummins small cam with an 8 speed manual tranny. I'm really excited! My mechanic is going through everything now. He just did the PM , all fresh oil in the differentials and new wheel seals , bearings and shoes on the drives. Next hes gonna tackle an exhaust leak. He also fixed all the lights and fixed the wiper fluid pump that wasn't working. The AC is not working but we don't have time to dig into that right now. Ok, now the fun stuff.... The cab lifter isn't working. He removed all the hydraulic lines and had the drivers side Piston rebuilt because it was leaking badly. That was a hassle... But after that the cab still won't lift. Hes removing the pump now and is taking it the same hydraulic guy. He thinks that needs a rebuild too and and maybe the check valve inside is bad. Anyone have any experience with this??? I really wanna get this cab up because he doesn't wanna put the new fuel filters and then not be able to prime it. TY Good to see a fellow MH guy. Jason, I just recently replaced my cab jack pump on my 93 MH. PowerPacker makes them and it was around $400 brand new. https://ohiohydraulic.com/power-packer-hp50034204-hand-pump-4000psi-35ci-69-spindle/ Also, beware when putting new fluid in that system. Don't mix hydraulic oils or use transmission fluid. It's recommended to use the military aerospace grade hydrulic oil MIL-H-5606A in that hydraulic system for the cab, especially if you are in cold winter area. This (or an equivalent)is technically the correct oil for that system. It's kinda pricy, but it's the recommended oil. I bought a gallons worth and they were super fast on shipping. https://www.aircraftspruce.com/catalog/lgpages/hydfluid5606qt_09-27000.php Edited yesterday at 01:56 PM by BottleHauler84 Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted 21 hours ago Share Posted 21 hours ago Being a '91 it should have a Big Cam NT88 so if it has a small cam the engine has been changed. By 1992 I think the N-14 was out. If a NT88 350 it will be a CPL 840, good engine, I had many miles on one. When you get the cab up, post the CPL number off the engine tag, that will ID it. If he pre filled the filter, it will start and clear itself. May run rough until the air is out, but I have changed a few from underneath. Quote Link to comment Share on other sites More sharing options...
mowerman Posted 17 minutes ago Share Posted 17 minutes ago Looks great good luck. I was also thinking the same thing. Small cam doesn’t sound right….. bob Quote Link to comment Share on other sites More sharing options...
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