HomeCummins/OnanCummins/Onan DMDB

Cummins/Onan DMDB Generator Set

The Cummins/Onan DMDB is a generator set powered by a Cummins/Onan NTTA-855-G2 engine. It is available at 127 V, 220 V, 139 V, 240 V and 380 V. It holds about 31 L (8.2 gal) of oil and 66.9 L (17.7 gal) of coolant.

31.0 L
Oil capacity
1
Document types

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

Service parts for the DMDB

Grouped by system, with how many of each the parts manual calls for.

Air intake

1 required

Fuel system

1 required

Oil system

1 required

Cooling system

1 required
8342-1Coolant filtersee priceAmazon

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

Oil capacity31.0 L
Voltage options127 V, 220 V, 139 V, 240 V, 380 V
Battery voltage24.0 V
Battery quantity2
Coolant capacity66.9 L

Engine

Cummins/Onan NTTA-855-G2
Oil capacity31.0 L

Maintenance & consumables

for the Cummins/Onan NTTA-855-G2
ItemSpecCapacityPart #Interval
Air filterAIR FILTER8342-1 Amazon eBay FridayParts $44.80
Fuel filterFUEL FILTER8342-1 Amazon eBay FridayParts $44.80
Oil filterLUBRICATION OIL FILTER8342-1 Amazon eBay FridayParts $44.80
Battery1000 hr
Belt
Coolant
Coolant filterCOOLANT FILTER8342-1 Amazon eBay FridayParts $44.80
Oil
Spark plug

Common questions

What engine is in the Cummins/Onan DMDB?

The Cummins/Onan DMDB is powered by the Cummins/Onan NTTA-855-G2 engine.

What's the oil capacity on a Cummins/Onan DMDB?

The Cummins/Onan NTTA-855-G2 engine in the Cummins/Onan DMDB has an oil capacity of 31.0 liters.

Which oil filter part number does the Cummins/Onan DMDB take?

The Cummins/Onan DMDB uses oil filter part number 8342-1.

Which fuel filter part number does the Cummins/Onan DMDB take?

The Cummins/Onan DMDB uses fuel filter part number 8342-1.

What air filter fits the Cummins/Onan DMDB?

The Cummins/Onan DMDB uses air filter part number 8342-1.

Troubleshooting

6

Symptoms & remedies

SymptomRemedy
Green RUN lamp lights following engine Start-up.Indicates all engine systems are normal. No corrective action required.
PRE HI ENGINE TEMP lamp lights. Engine continues to operate.Indicates engine 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 shut down, use the following: a. Reduce load if possible by turning off non-critical loads. b. Check air inlets and outlets and remove any obstructions to airflow. c. 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 down.Indicates engine 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 with the following checks: a. Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary. b. Check for obstructions to cooling airflow and correct as necessary. c. Check for slipping fan belt, tighten if loose. d. Reset control and restart after locating and correcting problem. Contact your distributor if none of the above applies.
PRELO OIL PRES lamp lights. Engine continues to operate.Indicates engine 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 procedure in step 5.
LO OIL PRES lamp lights. Engine shuts down.Indicates engine oil pressure has dropped to 14 psi (97 kPa). Check oil level, replenish as necessary. Check oil lines and filters for leaks, repair as required. Reset control and restart. Contact your 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.A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. Engine runs, shuts down, and LO OIL PRES lamp lights. b. Check for dirty fuel filter and replace if necessary (see MAINTENANCE section). c. Check for dirty or plugged air filter and replace if necessary (see MAINTENANCE section). d. Refer to step 5. e. Reset the control and restart after correcting the problem. Contact your distributor for service if none of the above applies.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing. Full Cummins/Onan DMDB troubleshooting guide (19 entries) →

Parts

1
Part #DescriptionQtySystem
8342-1AIR FILTERAir filter Amazon eBay FridayParts $44.80

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

Service manual — 903-0124 Onan DB DC Series Operators 15-150KW (4-1987) (Cummins/Onan)