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catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 2366
Experience:  Field service technician for CAT 19 years.
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My CAT 623B scaper will not shift above second gear. WHY?

Customer Question

My CAT 623B scaper will not shift above second gear. WHY? All fuids OK.
Submitted: 2 years ago.
Category: Construction and Road Equipment
Expert:  catmastertech replied 2 years ago.


The most common issue for no auto shift is due to low engine speed.

This can be from plugged fuel filters, plugged air filters, dragging brakes, turbo boost leak or worn or misadjusted throttle linkage.

If engine does not reach the proper speed, the transmission will not reach the proper speed for autoshift to work.

1st to 2nd does not require the same speeds to shift, generally it will shift once the machine is moving.

Expert:  catmastertech replied 2 years ago.

Please post the full machine serial number if you need more help with this.

Engine rpm must be high enough to get the transmission rpm up to the shift point.

If you just rebuild the engine, the fuel settings may be wrong. Did the fuel shop set the pump to the machine's original fuel system settings?