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Cummins/Onan DFM 300 Generator Set

The Cummins/Onan DFM 300 is a 300 kW (375 kVA) Diesel standby generator set powered by a Cummins/Onan NTA-855-G2 engine. It is available at , 3-phase and 60 Hz. It holds about 31 L (8.2 gal) of oil and 72 L (19.0 gal) of coolant. Starting uses 2 group-8 batteries at 12 V. The set weighs about 3019 kg (6656 lb).

300 kW
Standby
14.0 L
Displacement
31.0 L
Oil capacity
0
Document types

How to read your Cummins/Onan serial & model number →

Typical fuel consumption for 300–305 kW Diesel generators →

Compare with other 300–305 kW Diesel generators →

Specifications

FuelDiesel
Frequency60.0 Hz
Standby power300 kW
Standby kVA375
Oil capacity31.0 L
Alternator3 Phase 60 Hz YB
Phase3
Power factor0.8
Battery group8D
Battery voltage12 V
Battery quantity2
Coolant capacity72 L
Dry weight3019 kg

Engine

Cummins/Onan NTA-855-G2
Oil capacity31.0 L
Coolant capacity20.8 L
Displacement14.0 L
AspirationTurbocharged and Aftercooled
Rated speed1800 rpm

Filters for the Cummins/Onan NTA-855-G2

8

Engine-mounted filters the filter manufacturers list for this engine family. These come from the engine, not from this generator set’s own parts list, so confirm against your serial number before ordering.

SystemFilterDescriptionCross-references
Oil filterP551670Lube Filter, Spin-On Full FlowCUMMINS 298670, CUMMINS 299670, NAPA 1970, CARBOCOL 0026 FridayParts $26.68
Oil filterP550777Lube Filter, Spin-On BypassCUMMINS 3021658, CUMMINS 33004232, NAPA 1749, BALDWIN B7577 FridayParts $43.56
Fuel filterP550105Fuel Filter, Spin-On PrimaryCUMMINS 154700, CUMMINS 154710, NAPA 3109, NAPA 3405 buy
Fuel filterP557440Fuel Filter, Spin-On SecondaryCUMMINS BM78672, BALDWIN BF970, LPM 00013505994, WALGAHN-MOTORENTECHN 00811464 FridayParts $189.69
Fuel / water separatorP558000Fuel Filter, Water Separator Spin-On Twist&DrainCUMMINS 3308638, CUMMINS 3308683, NAPA 3405, NAPA 3693 KuduParts $24.00 FridayParts $25.66
Fuel / water separatorP550106Fuel Filter, Water Separator Spin-OnCUMMINS 154789, CUMMINS 156164, NAPA 3405, BALDWIN BF957-D FridayParts $285.60
Coolant filterP554071Coolant Filter, Spin-OnCUMMINS 209604, CUMMINS 209606, NAPA 4071, WALGAHN-MOTORENTECHN 00811412 FridayParts $397.60
Coolant filterP554073Coolant Filter, Spin-OnCUMMINS 209605, CUMMINS 209607, NAPA 4073, VERSATILE 00104040 KuduParts $40.00

Maintenance & consumables

for the Cummins/Onan NTA-855-G2
ItemSpecCapacityPart #Interval
Air filter—
Fuel filter—
Oil filter—465 hr
Battery127 A/hr—
Belt—
Coolant84.8 Litres—
Oil38.6 Litres38.6 Litres—
Spark plug—

Common questions

How many kW is the Cummins/Onan DFM 300?

The Cummins/Onan DFM 300 is rated 300 kW standby (375.0 kVA).

Which engine powers the Cummins/Onan DFM 300?

The Cummins/Onan DFM 300 is powered by the Cummins/Onan NTA-855-G2 engine.

What kind of fuel does the Cummins/Onan DFM 300 run on?

The Cummins/Onan DFM 300 runs on Diesel.

What is the oil capacity of the Cummins/Onan DFM 300?

The Cummins/Onan NTA-855-G2 engine in the Cummins/Onan DFM 300 has an oil capacity of 31.0 liters.

How much coolant does the Cummins/Onan DFM 300 hold?

The Cummins/Onan DFM 300 cooling system holds 72 liters (19.0 US gallons) for the radiator system including the engine, per the manufacturer specification sheet.

What is the dry weight of the Cummins/Onan DFM 300?

The Cummins/Onan DFM 300 has a dry weight of 3019 kg (6655 lb).

What battery does the Cummins/Onan DFM 300 use?

The Cummins/Onan DFM 300 uses 2 batteryies, 12 V each, group 8D, per the manufacturer specification sheet.

What alternator comes on the Cummins/Onan DFM 300?

The Cummins/Onan DFM 300 uses a 3 Phase 60 Hz YB alternator.

Troubleshooting

6

Symptoms & remedies

SymptomCauseRemedy
Green RUN lamp lights following engine start-upIndicates all engine systems are normal. No corrective action required.
PRE HI ENGINE TEMP lamp lights. Engine continues to operateEngine has begun to overheat and engine temperature has risen to approximately 205°F (97°C)If generator is powering non-critical and critical loads and cannot be shutdown, reduce load if possible by turning off non-critical loads; check air inlets and outlets and remove any obstructions to airflow; open doors or windows in generator area to increase ventilation; if engine can be stopped, follow procedure in step 3
HI ENG TEMP lamp lights. Engine shuts downEngine has overheated (engine temperature has risen above 215°F/102°C) or coolant level is low (sets with coolant level sensor)Allow engine to cool down completely before proceeding: check coolant level and replenish if low; look for possible coolant leakage points and repair if necessary; check for obstructions to cooling airflow and correct as necessary; check for a slipping fan belt and tighten if loose; reset control and restart after locating and correcting problem; contact an Onan Dealer or Distributor if none of the above
PRE LO OIL PRES lamp lights. Engine continues to operateEngine oil pressure has dropped to 20 psi (138 kPa)If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow step 5 procedure; if engine can be stopped, follow procedures in step 5
LO OIL PRES lamp lights. Engine shuts downEngine oil pressure has dropped to 14 psi (97 kPa)Check oil level, lines and filters; if oil system is okay but oil level is low, replenish; reset control and restart; contact an Onan Dealer or Distributor if oil pressure is not in the range of 50 to 70 psi (345 to 483 kPa)
OVERCRANK lamp lights and engine stops cranking; or engine runs, shuts down, and LO OIL PRES lamp lightsPossible fuel system problemCheck for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required; check for dirty fuel filter and replace if necessary (see MAINTENANCE section); check for dirty or plugged air filter and replace if necessary (see MAINTENANCE section); refer to Step 5; reset the control and restart after correcting the problem; contact an Onan Dealer or Distributor for service if none of the above

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing. Full Cummins/Onan DFM 300 troubleshooting guide (24 entries) →

Parts

1
Part #DescriptionQtySystem
E204747Coolant heater 240/480V 6420W 1PHService part / kit eBay $1948.00

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Available documents

Operator's manual — 960-0133 Onan DFM DFP Diesel Genset Operator's manual (10-1986) (Onan)

This page was generated from the 1 manufacturer document above by automated extraction; every figure shown is copied from one of them. How the data is compiled.