How to Quiet a Cummins Onan 4000 Generator

To learn how to quiet your Cummins Onan 4000 generator, you should read this article. In this article, we’ll talk about Sound-controlled muffler, Resonator, Isolation mount, and Cleanup. These steps will drastically reduce the noise generated by your generator. If you’re having trouble determining the right product for your needs, read on. You may also be surprised to learn that a sound-controlled muffler will actually work much better than you think it will.

OnlySilent featured on media
Disclosure : Some of the links below are affiliate links, meaning at no additional cost, I will earn a commission if you click through and make a purchase. As an Amazon Associate, I earn from qualifying purchases.

Sound-controlled muffler

The Cummins Onan 4000 generator features a sound-controlled muffler that helps lower noise levels. It is approved for use in national parks and other sites where the noise level can cause a disruption to the environment. The unit features four-point vibration isolation and a complete muffler. It is compliant with CARB Tier III and EPA Phase 3 emission standards, making it legal in all 50 states.

When installing the muffler, the exhaust pipe should be disconnected and secured. Then, you must remove the existing exhaust pipe and muffler assembly. The new muffler must then be mounted to the exhaust pipe, and all loose parts should be removed and secured. If the unit has expansion joints, remove them so the new muffler can properly seal. Afterward, you must check the exhaust pipe for leaks and tighten them.


If you’re wondering how to quiet Onan 4000 generators, you should know that you can’t add a rectifier. The microquiet series uses a special spark plug that works with Onan generators. Unlike regular AC generators, an Onan’s microquiet system smooths out the AC output at low rpm. Here are a few tips to help you quiet your Onan generators.

READ ALSO :   Why Will Power Supply Make Noise?

First, don’t use sound deadening materials that aren’t designed to withstand high levels of noise. Self-stick MAT66 or KilMat can be used to reduce sound inside a closet or cabinet. Another option is to install a long exhaust pipe. This can be installed over the roof, but the sound will be transferred with it. Don’t use these methods if you can’t get clearance for the generator.

Isolation mount

An isolation mount for an Onan 4000 generator is a necessary accessory for this motorhome product. A motorhome engine is a hot commodity and should be cooled properly. An isolator will prevent noise, vibration, and hum from penetrating the motorhome’s interior. The engine is one cylinder and runs at a speed of 3,600 RPM. This engine generates significant vibration. Vibration isolators allow the engine to shake but not to transfer this vibration to the motorhome. Because the engine is tuned for 3,600 RPM, this type of mount isn’t an ideal fit for low-speed engines.

A second type of isolation mount is required to protect the fuel tank from vibration. The fuel tank is spring-isolated and attached under the frame rails of the generator set. Alternatively, it can be mounted on a base using elastomeric pads. The primary cost for an isolation mount is a secondary set of isolators. However, a secondary set of isolators is a successful solution.


There are many ways to maintain an Onan 4000 generator. Regular maintenance and exercise can help extend its life. Onan recommends running the generator for two hours each month at half-load to remove moisture and keep parts lubricated. Here are a few tips for keeping your Onan generator running smoothly. This way, you can avoid costly repairs later. Listed below are the most common ways to perform generator clean-up.

READ ALSO :   How to Quiet a Jet Pump

– Check the oil weight of the Onan 4000 generator. The oil weight varies depending on the temperature and location. Check your owner’s manual to determine how much oil is necessary for your generator. Onan generators use different types of oil. Use the right type of oil for the model and region you live in. To maintain the performance of your Onan 4000 generator, you will need to conduct regular maintenance.


If you’re interested in a quiet generator, the Onan 4000 model might be the perfect choice. Its 60-decibel sound level is perfect for driving in National Parks. Though it’s discontinued, you can still find it for as low as $2500. The Onan 4000 generator is USDA Forest Service approved, and it meets National Park Service sound level requirements. In addition, it’s built with vibration isolation to reduce noise.

The Onan 4000 is an excellent option for RV use. Its low-noise design is a major advantage, especially if you’re travelling through national parks or forests. It also has a 4-cycle liquid-cooled diesel engine and microprocessor-based controls to minimize noise and vibration. This quiet Onan generator meets the noise standards of the USDA Forest Service and National Park Service, which make it a perfect choice for RVs.