1. The Challenge: Significant Internal Engine Damage

The Cummins QSK23 generator engine arrived at DSL with extensive internal damage requiring a complete overhaul.

During teardown, technicians identified:

●      A dropped valve causing internal engine damage.

●      Seized camshaft bearings requiring corrective work.

●      Additional engine block machining requirements.

●      Electronic faults that needed diagnosis after mechanical repairs.

Given the extent of the damage, DSL approached the repair as a complete engine overhaul, addressing the mechanical, machining, and electronic issues to restore reliable operation.

2. Complete Engine Overhaul

The engine was completely disassembled to allow a detailed inspection of the internal components and identify the full extent of the damage.

The overhaul included:

1. Complete engine teardown and inspection.

2. Assessment of damage caused by the dropped valve.

3. Inspection and repair of components affected by the seized camshaft bearings.

4. Repair or replacement of damaged components as required.

5. Restoration and reassembly of the engine following the applicable specifications for the QSK23 platform.

The objective was not simply to get the engine running again, but to systematically address the damage identified during the teardown and establish a sound foundation for the remaining machining and electronic work.

3. Precision Machining & Engine Block Restoration

The engine block required precision machining as part of the rebuild. DSL performed align boring to restore bearing bore alignment and sleeving as required.

This precision work restored critical dimensions and alignment, providing a solid foundation for proper reassembly and reliable engine operation.

4. Electronic Diagnostics Revealed Additional Problems

After the mechanical overhaul and machining, the engine continued to show electronic performance issues.

Diagnostics identified:

●      Internal ECM faults

●      Deteriorated engine wiring harness

These findings highlighted the need to address both mechanical and electronic systems. DSL continued troubleshooting to identify and resolve the underlying electronic issues before final testing.

5. Advanced Diagnostics With Cummins Australia Support

The electronic issues required advanced troubleshooting, so DSL worked with Cummins Australia technical support to diagnose the ECM faults and wiring harness problems.

The ECM faults were resolved, and the deteriorated wiring harness was repaired or addressed as required. This ensured the electronic systems were functioning correctly alongside the completed mechanical rebuild.

6. Systematic Repair & Corrective Actions

The QSK23 repair required coordinated mechanical, machining, and electronic work. Key corrective actions included:

1. Complete teardown and inspection – Identified the extent of internal damage.

2. Internal damage repair – Addressed damage from the dropped valve and seized camshaft bearings.

3. Engine overhaul – Rebuilt the engine to required specifications.

4. Precision align boring – Restored proper bearing bore alignment.

5. Engine block sleeving – Completed as required during restoration.

6. Electronic diagnostics – Investigated remaining control-system issues.

7. ECM fault resolution – Identified and resolved internal ECM faults.

8. Wiring harness repair – Addressed deterioration in the engine wiring harness.

9. Cummins technical support – Worked with Cummins Australia during electronic diagnostics.

10. Final performance testing – Verified operation through continuous load bank testing.

7. Four-Hour Load Bank Testing

After completing the mechanical, machining, and electronic repairs, the Cummins QSK23 underwent four hours of continuous load bank testing.

All monitored parameters remained within specification throughout the test. This confirmed that the rebuilt mechanical and electronic systems were operating reliably under sustained load before the engine returned to service.