Cummins/Onan GTA14 / GTA14 qi 20 NA — Intake & Exhaust Valve Procedure
Adjustments · Valve train
For the Cummins/Onan GTA14 / GTA14 qi 20 NA, from the Cummins/Onan owner's manual.
Applies to: Cummins/Onan GTA14 qi 20 NA, Cummins/Onan GTA14 engine
Before you start
- Do not pull or pry on the fan to rotate the engine
Procedure
- Disconnect battery and remove rocker housing covers.
- Tighten rocker lever shaft cap-screws.
- Tighten rocker lever housing cap-screws in sequence 1 through 6, then 7 and 8.
- Rotate accessory drive nut clockwise to align 1-6 VS mark with pointer.
- Confirm both valves closed on cylinder No. 1.
- Loosen lock nuts on intake and exhaust adjusting screws.
- Insert correct feeler gauge between crosshead top and rocker lever pad.
- Tighten adjusting screw (torque wrench or feel method) and hold while tightening lock nut.
- Recheck feeler gauge drag; adjust all valves in firing order 1-5-3-6-2-4.
- Install rocker lever covers.
Tools required
- Feeler gauges Amazon
- Inch pound torque wrench Part No. 3376592 Amazon
- Torque wrench adapter Part No. ST-669 Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Rocker shaft cap-screws 156 Nm [115 ft-lb]
- Rocker housing cap-screws 1-6: 115 Nm [85 ft-lb]; 7 & 8: 47 Nm [35 ft-lb]
- Intake valve lash 0.35 mm [0.014 inch]
- Exhaust valve lash 0.85 mm [0.033 inch]
- Adjusting screw 0.56-0.68 Nm [5-6 in-lb]
- Lock nut with adapter 54 Nm [40 ft-lb]; without 68 Nm [50 ft-lb]
- Rocker covers 12 Nm [105 in-lb]
Full service-parts list: Cummins/Onan GTA14 qi 20 NA →
Source: Cummins/Onan owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.