Cummins/Onan QSX15 / QSx15 — Engine Brake Assembly - Adjust
Adjustments
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
- To get maximum brake operating efficiency and to prevent engine damage, follow instructions in this section.
Procedure
- Remove eight capscrews, isolator assemblies, rocker lever cover, and rocker lever cover gasket.
- Locate engine brake set marks: BRAKE SET 1-6, 2-5, 3-4.
- Rotate engine clockwise until set mark aligns with stamped mark on front gear cover.
- Verify both intake and exhaust valves on cylinder are closed and camshaft follower is on inner base circle.
- Press engine brake lever down to verify follower contacts camshaft.
- Loosen locknut on brake lever adjusting screw and back out one turn.
- Insert feeler gauge Part No. 3163530 between bottom of engine brake piston and top of exhaust valve pin.
- Tighten adjusting screw until drag on feeler gauge is felt.
- Hold adjusting screw and tighten locknut to 20 Nm [15 ft-lb]. Remove feeler gauge.
- Repeat on remaining cylinders.
- Install rocker lever cover gasket, cover, isolators, and capscrews. Tighten to 25 Nm [18 ft-lb].
Tools required
- 3163530 Brake Feeler Gauge - 7.00 mm [0.276 in] Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Engine brake adjustment: 7.0 mm [0.276 in]
- Engine brake adjusting screw locknut: 20 Nm [15 ft-lb]
- Rocker lever cover capscrews: 25 Nm [18 ft-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.