4939034 | Genuine Cummins® Exhaust Muffler

• Cummins Onan® Commercial & RV Generators: Select commercial mobile, utility, and standby generator models.

• Onan® Industrial Engine Series: Compact multi-cylinder gasoline, LP, and diesel engine power units utilized in industrial equipment, welders, and utility machinery.

• Power Generation Equipment: Mobile power units, auxiliary power units (APUs), and stationary generator sets (G-Drive / Gensets).

1. What is it?

Part is a heavy-duty cylindrical exhaust silencer installed in the exhaust system downstream of the engine exhaust manifold or flexible exhaust tube. It calms expanding combustion gases to suppress engine noise and safely channels exhaust gases outside the generator enclosure or vehicle body.

2. Core Functions & Technical Features

• Acoustic Attenuation (Noise Reduction): Reduces decibel levels produced by internal combustion pulses, ensuring compliance with strict US Forest Service and RV park noise regulations.

• Integrated Spark Arrestor: Features a specialized internal screen or baffle system that captures glowing carbon particles and sparks before they exit the exhaust pipe, preventing fire hazards in dry/forested environments.

• Corrosion & Heat Resistance: Constructed from heavy-gauge aluminized steel or stainless steel to withstand high-temperature exhaust flow, thermal expansion, and weather exposure.

• Backpressure Management: Designed with precise internal baffling to minimize engine backpressure, ensuring optimal power output and fuel efficiency for Onan® power units.

1. Excessive Engine Noise (Loud Exhaust Pop or Roar)

• Symptom: The generator or engine operates at a noticeably higher decibel level, producing a sharp popping, rattling, or roaring noise during operation.

• Cause: Internal baffle collapse, structural rust holes, or split seams along the muffler casing.

2. Exhaust Gas Leaks & Carbon Soot Accumulation

• Symptom: Black carbon soot buildup inside the generator compartment or visible smoke escaping directly from around the muffler casing rather than the tailpipe outlet.

• Cause: Cracking along weld seams or severe rust perforation in the aluminized steel shell.

3. Loss of Engine Power or Generator Stalling Under Load

• Symptom: The generator starts normally but bogs down, struggles under electrical load, or stalls completely after running for a short period.

• Cause: Clogged internal spark arrestor screen or collapsed internal baffles creating excessive exhaust backpressure.

4. Burning Odor or Fire Hazard Warning (Spark Escaping)

• Symptom: Visible sparks or glowing embers exiting the tailpipe, or a strong smell of hot metal/exhaust inside the equipment enclosure.

• Cause: Degradation or burnout of the integrated internal spark arrestor screen, allowing unburned carbon embers to pass through.