Cummins/Onan — Returning the Set to Operation
Maintenance · Engine
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Do not smoke while servicing batteries. Explosive gases are emitted from batteries in operation.
Procedure
- CHECK SERVICE IDENTIFICATION TAGS to properly service engine.
- Uncover and remove all storage seals from engine. Remove any dust, dirt, or foreign matter.
- CHECK fuel supply tanks. CHECK lubricating oil for moisture or contamination (drain if necessary). CHECK fuel line connections, all wiring connections, and exhaust line connections.
- Service air cleaner per maintenance schedule.
- Check tag on oil base and verify that oil viscosity is still correct for existing ambient temperature.
- Clean and check battery. Measure specific gravity (1.260 at 25°C [77°F]) and verify level to be at split ring. If specific gravity is low, charge until correct value is obtained. If level is low, add
- Check engine for fuel or oil leaks. Correct leakage as required.
- Install fully charged batteries.
- Clean and regap spark plugs.
- Start engine and check while running for leaks, battery charge rate, and proper cooling.
Tools required
- Hydrometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Battery specific gravity: 1.260 at 25°C (77°F)
Source: Cummins/Onan service 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.