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Home›Repair guides›Cummins/Onan›Alternator and Engine Installation

Cummins/Onan — Alternator and Engine Installation

Repair & overhaul

From a Cummins/Onan service manual covering: C13 N6H, C13N6H, C17 N6H, C17N6H, C20 N6, C20N6H, RS13A. Check it applies to your exact model before use.

Applies to: Cummins/Onan C13 N6H, Cummins/Onan C17 N6H, Cummins/Onan C20 N6, Cummins/Onan RS13A

Before you start

  • Do not allow contact between the rotor and stator windings.

Procedure

  1. Install the dipstick with a bead of Loctite 518 on the threads. Reposition the engine.
  2. Install the engine isolator bolts. Torque to 24-29 Nm (17.7-24.1 lb-ft).
  3. Install the alternator rotor (and/or stator), sliding the rotor onto the engine taper and threading the through-bolt by hand until it bottoms out.
  4. Install the alternator isolator bolts. Torque to 24 - 29 Nm (17.7 - 24.1 lb-ft).
  5. Check the engine oil level and add or drain oil as needed.
  6. Install the intake manifold with new gaskets. Torque the nuts to 11 - 14 Nm (97 - 124 lb-in).
  7. Install the governor actuator linkage onto the throttle shaft.
  8. Install the exhaust manifold and mixer assembly using new gaskets. Torque the nuts to 33 - 40 Nm (24.3 - 29.5 lb-ft).
  9. Install the airbox and air filter. Torque the mounting bolts and mixer nuts to 3.2 - 4.0 Nm (28 - 35 lb-in).
  10. Make the electrical connections to the alternator heater, oil level switch, and oil plug heater.
  11. Route the wiring and thread the battery cables and alternator leads through the grommeted holes.
  12. Attach the cables to the starter, install the endbell, connect the positive cable, and connect the alternator leads to the circuit breaker.
  13. Install the oil cooler, inner panels, muffler, alternator fan, and brush block; torque per the torque table.
  14. Install the battery and battery cables, intake and exhaust enclosure panels, and crossbars/hood.
  15. Restore power to the AC accessories, turn on the fuel supply, open the circuit breaker, and test run the generator set.

Tools required

  • General mechanical tools
  • Torque wrench Amazon

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Engine isolator bolts: 24-29 Nm
  • Alternator isolator bolts: 24 - 29 Nm
  • Intake manifold nuts: 11 - 14 Nm
  • Exhaust manifold nuts: 33 - 40 Nm
  • Airbox/mixer bolts: 3.2 - 4.0 Nm
  • Alternator fan through-stud nut: 113 - 139 Nm
  • Stator through-bolt nuts initial 27 - 33 Nm, final 38 - 42 Nm

Full service-parts list: Cummins/Onan C20 N6 →

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.

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