Cummins/Onan QSX15 / QSx15 — Overhead Set - Adjust
Adjustments · valve train
For the Cummins/Onan QSX15 / QSx15, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan QSx15, Cummins/Onan QSX15 engine
Before you start
- Do not use solvent to clean rocker cover gasket.
- Batteries can emit explosive gases. Disconnect battery before service.
Procedure
- Disconnect battery.
- Locate valve set marks on outside of vibration damper: A adjusts cylinders 1 or 6, B adjusts cylinders 2 or 5, C adjusts cylinders 3 or 4.
- Rotate engine clockwise to align set mark with pointer. Check both valves are closed.
- Loosen injector adjusting screw locknut. Use dial-type torque wrench to tighten injector rocker lever adjusting screw.
- Back out adjusting screw one or two turns. Tighten injector adjusting screw to 8 Nm [70 in-lb].
- Hold injector lever adjusting screw and tighten locknut to 75 Nm [55 ft-lb].
- Set valves on same cylinder using feeler gauge: intake 0.36 mm [0.014 in], exhaust 0.69 mm [0.027 in].
- Tighten valve adjusting screw to 0.6 Nm [5 in-lb]. Hold screw and tighten locknut to 45 Nm [33 ft-lb].
- Repeat for all cylinders following firing order 1-5-3-6-2-4.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Intake valve lash: 0.36 mm [0.014 in]
- Exhaust valve lash: 0.69 mm [0.027 in]
- Injector lash adjustment torque: 8 Nm [70 in-lb]
Full service-parts list: Cummins/Onan QSx15 →
Source: Cummins/Onan operator'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.