2006 38z 14551 miles new transmission,same truck 6221 miles since tansmission replacement,gotta go back for another tranny what is the deal with Mack,they used to have a good off-road truck,now I like every one else is getting tired of it, we need a new truck for pumps that the manufacturers are gonna push and have at their disposal to mount on,Macks just aint cutting it anymore

I have a 1996 mach with 380,000,Had to put two in also.

Ruck

what no radiators

Pudg-

 high range? 

Is Mack using Fullers?? We used to lose high range syncros if you didn't put it in neutral,flip into hi range ,put it in reverse then into pump gear. I drive an Mack-A -Matic,so I've forgotten how to shift

The tranny in the 42m in my pics, I went through 2 tranny rebuilds 363 days apart, the warranty was over i n 2 days. the high range went out somehow. 4th gear for about 20 miles to get back to the yard as directed by the shop boss. didnt time it, just knew it took a long time.

hi-range

 When a good mechanic disassembles the transmission he can tell by the sychronizer if the truck is being driven properly.The key is to NEVER range shift unless the transmission is engaged in a gear.When putting a truck in PTO you must first,depress clutch,then put in low or 1,with it in that gear flip the lever in to high range and pull the PTO engagment switch .With the range lever in high , PTO air valve pulled,in first gear,clutch in,shift to your desired gear,usually 7th,then release the clutch slowly engaging your system.When passing through nuetral you will hear the tranny go in to high range and PTO box engage.Again ,while driving you must ALWAYS pre-select,whether to HI or LO, while in a gear,NEVER in nuetral,this is what tears up the sychronizer.

Pre selection is one of the things to get good service out of either Mack of Fuller transmissions. We also change the gear oil every time we change engine oil.

When I first started running a pump with a lo and hi range trans, The procedure for going into pump gear was:

Depress clutch, select a gear, (as if you are going to drive),flip into Hi-range, go to Reverse and slowly release clutch, until you feel clutch start to grab,Depress clutch,Now go to Pump gear, (determined by Pump Manufacturer), actuate PTO lever and release clutch.

Think of it as pre-loading the synchronizer to make sure that it is fully engaged.

Bisley57 is correct in advising preselection while still in gear when going from lo to hi.

Bisley

that all depends on who you talk to some say preselecting is bad,others say preselect is rite,we all preselect here,as far as the tranny goes its been a problem since I drove it from Wisconsin, it has always grinded the first low to high shift in the morning after that it would not the rest of the day,whos rite whos wrong I donot know but if thats whats tearing up transmissions seems as though they would send a statement telling truck owners such,they donot want to take a stand one way or the other because I dont think they know themselves

 There is a sticker on the console that tells you to pre-select.In the morning before the truck moves I always put the truck in pump gear,engage the PTO,but do not "boot" the machine.This gets tranny and steibel box warm and will prevent any grinding with the first lo to hi shift.