Mack T2180 trans with no high gears.

This topic contains 3 replies and was last updated by Array 11 years 4 months ago
September 21st, 2010 8:33pm
Truck is used daily but this morning would not give me the high gears. The box on top of the tarnsmission seems to provide air to the cylinder at the back of the trans and the driveline moves slightly when you flip the switch back and forth. It seems to be stuck??? I have put oil down the feed lines. Should I just pull that cylinder and see what we have going on in there or will this open up a can of worms for a novice heavy mechanic? Thanks in advance
September 22nd, 2010 10:58pm
Yes, it definitely sounds like range selector problems. What kind of trans is it? For instance, an Eaton 10 speed has a range selector with a cylinder on the back.

Are there air leaks?

The air pressure for those lines is likely 70-80 psi. Do you have enough?

The air seems to be passing through the shift handle on the stick, does it feels like it is shifting the valves like before? Do you get the click?
September 22nd, 2010 11:32pm
Along with what jimo said I would also check the slave valve. Most likely its the Range Cylinder, but it could be slave valve not distributing enough pressure to the cylinder.
February 6th, 2011 8:42pm
If it is a mack tranny with 3 counter shafts it is likely in the back of the tranny the sincros go and then it will not go into hi range. To tell if it is the 3 shaft tranny look at the back of the tranny if it is shaped like a triangle its a 3 shafter. Good tranny but the sincros are the weak point

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