The Cummins/Onan MDJA is a 0.49 L 1-cylinder natural engine rated at 1800 rpm, producing up to 5.2 kW. It powers generator sets from Cummins/Onan. It holds 2.4 L (0.6 gal) of oil and 4 L (1.1 gal) of coolant.
Also known as: Onan MDJA
| Oil capacity | 2.4 L |
|---|---|
| Coolant capacity | 4.0 L |
| Displacement | 0.49 L |
| Cylinders | 1 |
| Aspiration | natural |
| Rated speed | 1800 rpm |
| Gross power | 5 kW |
| Symptom | Remedy |
|---|---|
| Do not work on energized equipment | Do not work on energized equipment. Unauthorized personnel must not be permitted near energized equipment. Induced voltage remains even after equipment is disconnected from the power source. Plan maintenance with authorized personnel so equipment can be de-energized and safely grounded. |
Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.
Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan MDJA.
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | — | 8 hr | find | ||
| Fuel filter | Secondary fuel filter | — | 3000 hr | find | |
| Oil filter | Spin-on oil filter; adds 1.0 pint (.47L) beyond base oil capacity | — | 200 hr | find | |
| Belt | flexible seamless tubing | — | find | ||
| Coolant | Optional heat-exchanger (captive water) cooling system capacity; 50/50 ethylene glycol/water mix recommended | 2.25 US quart | — | ||
| Oil | Crankcase oil, API CD/SE (CC/SE for first 50-hour fill only); use SAE grade per ambient-temperature chart | 100.0 US quart | — | 100 hr |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
Step-by-step procedures compiled from the Cummins/Onan service manual for this engine.
The Cummins/Onan MDJA engine has an oil capacity of 2.4 liters.
The Cummins/Onan MDJA has a displacement of 0.49 liters with 1 cylinders.
The Cummins/Onan MDJA powers 1 generator set(s), including Cummins/Onan MDJA.
The Cummins/Onan MDJA oil change interval is every 100 hours.
A commonly reported issue on generators using the Cummins/Onan MDJA is: Do not work on energized equipment. Fix: Do not work on energized equipment. Unauthorized personnel must not be permitted near energized equipment. Induced voltage remains even after equipment is disconnected from the power source. Plan maintenance with authorized personnel so equipment can be de-energized and safely grounded..