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Home›Engines›Cummins/Onan NT855C

Cummins/Onan NT855C Engine

The Cummins/Onan NT855C is an engine. It powers generator sets from Cummins/Onan, including the NT855.

Also known as: Cummins NT855C

On this pageSpecsGenerator setsFAQService intervalsTorque & specsFluidsProcedures

Engine specifications

Service intervals

15
ItemActionHoursMonthsNotes
SystemTest1 hrToCI quarterly: exercise system under full load for 1 hour
BatteryTest6 moLoad-test battery at each semi-annual visit
Coolant antifreezeChange12 moNCCI/RCI: antifreeze change once per year during contract term
Engine tune-upOther12 moAnnual: engine tune-up with parts
Fuel filtersChange12 moAnnual: change fuel filters
Generator sets and associated systemsInspect6 moSemi-annual inspection, testing and preventive maintenance (default unless Appendix A states otherwise)
Load bankTest12 moAnnual four (4) hour load bank test / emergency service operation with four (4) hours full load test once per year
Lube oilChange12 moCMC/HCF: additional services on second visit - lube, oil and filter change
Lube oil analysisTest12 moAnnual: lube oil analysis
OilChange12 moNCCI/RCI: oil shall be changed once every 12 months
Oil filter, fuel filter and air filterChange12 moNCCI: change once every 12 months during the contract period
Primary and bypass lube filtersChange12 moAnnual: change primary and bypass lube filters
Transfer switchLubricate12 moToCI annual: check, clean and lubricate transfer switches and breakers
Valve clearanceAdjust12 moToCI annual: check valve clearance
Water filtersChange12 moAnnual: change water filters

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

5
TypeItemValueUnitCondition
OtherExercise under full load1hourToCI quarterly
OtherFull load test duration4hoursOnce per year
OtherLoad bank data recording interval15minutesDuring load bank test
OtherLoad bank test load level80% of generator nameplate capacity4-hour resistive load bank test
OtherLoad bank test profile2 hours at 50%, 1 hour at 75%, 1 hour at 100%Annual four (4) hour load bank test

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

FluidGradeStandardAmbientCapacityNotes
Engine oilmeeting manufacturer's specsAdd crankcase oil (grade meeting manufacturer's specs) to correct level (SCI)

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

11
Automatic Transfer Switch Semi-Annual Service maintenance
  1. Verify proper operation of exerciser clock; adjust if necessary.
  2. Provide visual inspection of all contacts and connection points.
  3. Perform building load test if practical and inspect for proper transfer and re-transfer.
  4. Verify operation of all control lamps.
Battery and Battery Charger System Semi-Annual Service maintenance
  1. Clean all battery terminals; verify integrity of cables and connectors.
  2. Load-test battery.
  3. Measure specific gravity of each battery cell.
  4. Inspect electrolyte level and add fluid if necessary.
  5. Verify proper operation and float voltage of external battery charger.
  6. Verify and record output of engine alternator.
Controls Semi-Annual Service maintenance
  1. Verify and record output voltage and adjust voltage regulator, if necessary.
  2. Calibrate control meters.
  3. Verify and record output frequency and adjust governor, if necessary.
  4. Verify operation of all control panel lamps.
  5. Inspect for any loose connections, terminals or discoloration.
Coolant System Semi-Annual Service maintenance
  1. Inspect all clamps, verify condition of all hoses and identify any leaks.
  2. Verify proper operation of engine water jacket heater.
  3. Test coolant freeze point and verify coolant level.
  4. Test coolant additive package for proper corrosion inhibitors.
  5. Inspect belt condition and tension; correct as required.
  6. Inspect radiator core for visual blockage or obstructions.
  7. Inspect for proper operation of intake louvers.
  8. Verify proper operation of remote radiator and belt condition.
Cooling System Semi-Annual Service (SCI) maintenance
  1. Visual inspection of Radiator/Heat exchanger for leaks, damage and obstructions.
  2. Add coolant to correct level.
  3. Inspect radiator cap, gasket and sealing surface.
  4. Visual inspection of water pump and cooling system gaskets for leaks.
  5. Inspect belts for cracking and fraying.
  6. Check water jacket heater for proper operation and adjust thermostat setting as needed.
  7. Check belt tension.
  8. Inspect flexible water connections for cracking, leaks and pliability.
  9. Inspect pulleys for excessive wear.
  10. Analyze coolant for proper antifreeze percentage.
  11. Analyze coolant conditioner level and add supplemental coolant additive as needed.
  12. Tighten hose clamps as needed.
  13. Lubricate fan drive with bearing lubricant.
Engine Semi-Annual Service maintenance
  1. Verify and record oil pressure and water temperature.
  2. Test all safety shutdown circuits and alarms (overspeed, overcrank, low oil pressure, high water temp, low coolant level).
  3. Inspect air intake system (air filter, crankcase breather, turbocharger).
  4. Inspect muffler system and drain condensation trap; verify rain cap operation.
  5. Inspect engine starting system; verify cable integrity and connections.
  6. Inspect exhaust flex coupling and piping for leaks and proper connection.
  7. Check for abnormal vibration or noise.
  8. Inspect spark plugs, plug wires and distributor.
Fuel System Semi-Annual Service maintenance
  1. Inspect all fuel lines and hoses for leaks and general condition.
  2. Inspect day tank and float assembly for proper operation and leaks.
  3. Inspect fuel pump for leaks.
  4. Verify proper operation of governor and governor linkage.
  5. Check fuel level in primary supply tank.
  6. Drain water and sediment from fuel filter and fuel supply tanks.
Generator Semi-Annual Service maintenance
  1. Inspect and lubricate generator end bell bearing.
  2. Inspect brushes, brush holders and commutators.
  3. Inspect cooling screen and general condition of alternator.
  4. Inspect for abnormal vibration.
  5. Verify connections and insulation condition.
  6. Verify proper operation of shunt trip on mainline circuit breaker.
Lubrication System Semi-Annual Service (SCI) maintenance
  1. Add crankcase oil (grade meeting manufacturer's specs) to correct level.
  2. Inspect oil heater for proper operation and leaks.
  3. With engine running, check for excessive crankcase blow-by.
  4. Visually inspect front and rear crankshaft seals and lubrication system gaskets for leaks.
  5. Check crankcase breather, inspect hose and connections.
  6. Take oil sample and perform oil analysis.
Optional Load Bank Testing maintenance
  1. Perform 4-hour resistive load bank test at 80% of generator nameplate capacity.
  2. Record all performance data at fifteen minute intervals including oil pressure, water temperature, voltage and frequency.
  3. Identify proper operation of fuel system, cooling system and overall condition of engine/generator set.
  4. Load bank testing shall be performed with no interruption to the normal power supply.
Starting System Semi-Annual Service (SCI) maintenance
  1. Check electrolyte level and add as needed.
  2. Check and record battery charger amperage.
  3. Check battery charger and adjust float rate for optimum battery performance and life.
  4. With engine running, check and record alternator for proper charge rate.
  5. Check for proper cranking termination upon engine start.
  6. Clean lead acid battery terminals and apply corrosion inhibitor.
  7. Tighten battery cable connections as needed.
  8. Inspect and tighten starter motors, connections and wiring.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

Which generators use the Cummins/Onan NT855C engine?

The Cummins/Onan NT855C powers 1 generator set(s), including Cummins/Onan NT855.