The Cummins/Onan Quiet Diesel is an engine rated at 2400 rpm. It powers generator sets from Cummins/Onan, including the Quiet Diesel 12500, Quiet Diesel 5500 and Quiet Diesel 7500.
Also known as: Onan Quiet Diesel
| Rated speed | 2400 rpm |
|---|
| Symptom | Cause | Remedy |
|---|---|---|
| Circuit breaker trips | Overloaded circuit. | Turn off some of the electric load and reset the circuit breaker. |
| No electricity in coach | Tripped circuit breaker. | Reset the circuit breaker. Check at distribution panel and genset. |
| Automatic Transfer Switch failure | Possible issue with Coach’s Automatic Transfer Switch. | Contact your Cummins Authorized Onan RV service dealer. |
| No electric output at generator | Other issue. | Contact your Cummins Authorized Onan RV service dealer. |
| Fails to crank | Low battery. | Charge battery or replace defective battery. Bad battery connection. Clean and tighten all battery and cable connections. |
| Cranks slowly | Low battery. | Check battery voltage at generator. Bad battery connection. Clean and tighten all battery cable connections. Incorrect oil viscosity. Replace with recommended viscosity oil. |
| Cranks but won’t start | Fuel below generator pickup level in tank. | Add fuel. Carbon deposits on spark plug(s). Remove spark plug(s) and replace. Low oil level. Add oil. |
| Exhausting black smoke | Dirty air filter. | Replace air filter. Choke stuck or misadjusted. Contact your Cummins authorized Onan RV service dealer. |
| Unit runs then stops, or stops when driving around a corner | Low fuel level. | Add fuel. Low oil level. Add oil. Excess oil. Reduce engine oil level. |
| Diesel excessive smoke on startup | Faulty glow plug. | Contact your Cummins authorized Onan RV service dealer. |
| Unit starts and runs, then stops when the start switch is released | Low oil level. | Check and bring all oil up to the appropriate levels. |
| No AC output | Contact your Cummins authorized Onan RV service dealer. | |
| Unit runs then surges | 1. Loose or worn spark plug leads. | 1. Check spark plug leads at spark plug and ignition coil. 2. Defective ignition coil, wiring or control components. 2. Contact your Cummins Authorized Onan RV service dealer. 3. Faulty spark plug. 3. Remove spark plug and clean or replace. 4. Governor out of adjustment. 4. Contact your Cummins Authorized Onan RV service dealer. 5. Combustion air preheat malfunction. 5. Contact your Cummins Authorized Onan RV service dealer. 6. Carburetor icing. 6. Move carburetor pre-heater to the winter position. 7. Carburetor varnishing. 7. Try fuel system cleaner and contact dealer |
Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.
The Cummins/Onan Quiet Diesel powers 3 generator set(s), including Cummins/Onan Quiet Diesel 12500, Cummins/Onan Quiet Diesel 5500, Cummins/Onan Quiet Diesel 7500.