3 Best Muffler For Diesel Generator of 2026 to Stop Exhaust Leaks and Noise

1

Chamixx 1-3/8" Generator Exhaust Muffler 155-1258 155-1222 for Onan Cummins

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  9.3
• Brand
  Chamixx

Key specs2

OEM Part Compatibility

• Onan Cummins 155-1258
• Onan Cummins 155-1222

Inlet Pipe Dimension

1-3/8 in

Pros & cons32

Pros

• Direct-fit replacement for Onan Cummins part numbers 155-1258 and 155-1222
• Standard 1-3/8 inch connection matches dedicated generator exhaust piping
• Designed to restore exhaust flow on compatible Onan Cummins generator units

Cons

• Package does not list an included gasket, requiring separate verification
• Will not fit single-cylinder 178F or 186F Chinese diesel generator engines

2

Muffler & Gasket For China 178F 178FE 178FA 178FAE 5-7

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  8.8
• Brand
  POWER PRODUCTS

Key specs2

Supported Engine Series

• 178F and 178FE (5 HP to 7 HP)
• 178FA and 178FAE (5 HP to 7 HP)

Included Hardware

Exhaust gasket included

Pros & cons32

Pros

• Includes a dedicated mounting gasket to help prevent exhaust gas leaks
• Engineered for 5 HP to 7 HP Chinese diesel engines including 178F and 178FE
• Compatible with both standard and electric-start 178FA and 178FAE engines

Cons

• Not compatible with larger 10 HP 186F engines or Onan Cummins equipment
• Single-piece construction is not made for dual-muffler silent canopy frames

3

Lower &Upper Muffler For 186F 186FE 186FA 186FAE 10HP Silent

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  7.7
• Brand
  POWER PRODUCTS

Key specs2

Enclosure Configuration

Upper and lower sections for silent canopies

Supported Engine Series

• 186F and 186FE (10 HP)
• 186FA and 186FAE (10 HP)

Pros & cons32

Pros

• Includes lower and upper muffler sections for enclosed canopy exhaust systems
• Direct fit for 10 HP 186F, 186FE, 186FA, and 186FAE silent diesel engines
• Designed to match the internal routing geometry of silent generator canopies

Cons

• Gasket is not listed as included and should be confirmed before installation
• Will not fit smaller 5-7 HP 178F models or open-pipe Onan Cummins generators

Last update on 2026-10-20 / Affiliate links / Images, Product Titles, and Product Highlights from Amazon Product Advertising API

How do you verify that a replacement muffler will bolt directly to your diesel engine?

Check your engine identification plate for the exact model code or OEM part number before ordering. Replacement silencers are built around specific engine families, such as China 178F, 178FE, 178FA, and 178FAE 5-7 HP engines, or 186F, 186FE, 186FA, and 186FAE 10HP models. For Onan Cummins generators, match the original equipment part numbers directly, such as 155-1258 or 155-1222. Diesel exhaust flanges use exact bolt-hole spacing, so a generic slip-on fitment will fail to seal properly.

What is the difference between mufflers for open-frame and silent canopy diesel generators?

Enclosed diesel generators require multi-piece exhaust assemblies designed to route hot gases safely through the acoustic housing. For example, a 186F 10HP silent diesel generator relies on a dedicated lower and upper muffler assembly to clear internal clearances and exit the canopy vent. Open-frame models use a single-piece silencer that discharges straight out into open air. Installing an open-frame muffler inside a canopy can cause severe heat buildup and body clearance issues.

Do replacement diesel generator mufflers come with a new exhaust gasket?

Some replacement kits include a matching gasket, while others provide only the bare silencer body. Kits such as the replacement muffler for 178F, 178FE, 178FA, and 178FAE engines include both the muffler and gasket in the package. If your chosen silencer does not list an included flange gasket, you must order the matching seal separately. Reusing an old, crushed gasket allows raw diesel soot and noxious exhaust fumes to leak past the cylinder head before reaching the muffler.

What pipe diameter is used on Onan Cummins replacement mufflers?

Standard replacements for part numbers 155-1258 and 155-1222, such as the Chamixx exhaust muffler, feature a 1-3/8 inch inlet diameter. You should measure the outer diameter of your existing exhaust pipe to confirm a tight, leak-free connection prior to installation. A loose fit at the inlet collar permits toxic exhaust gas to bypass the sound baffles and creates dangerous vibration under engine load.

What causes exhaust leaks around a newly installed diesel generator muffler?

Exhaust leaks typically occur when mounting hardware is torqued unevenly or when the mating flange is bolted down without a fresh gasket. On engines like the 178F or 186F series, warping the exhaust flange can cause hot gases to bypass the silencer joint and damage mounting studs. Always verify that the exhaust port surface is clean of old carbon deposits and that the inlet flange sits completely flat before tightening the hardware.

Will replacing the muffler make a diesel generator completely silent?

A replacement muffler dampens harsh exhaust pulses and eliminates leaks, but it cannot silence mechanical engine noise, injector clatter, or cooling fan airflow. For single-cylinder diesel engines rated at 5-7 HP or 10HP, replacing a rusted or hollowed-out silencer restores factory backpressure and baffling. If your site requires near-silent operation without exhaust emissions, a small solar generator can supply backup electricity for sensitive gear without any engine noise.