Onan Marine Generator Maintenance

A common concern for boaters is how to maintain their Onan Marine generator. Not to worry -- Onan makes it easy with pre-packaged maintenance Cruise Kits.

Easy Maintenance

In addition to the convenience of the Onan Cruise Kit, the sturdy container can be used to store additional parts related to the boat's electrical/machinery system. Part numbers of each of the components in the kit can be retrieved from the maintenance label on the generator set.

Maintaining a generator is similar to maintaining an automobile and maintenance is essential for top performance and long life. Just like a car, you will have an operator's manual for your generator unit with very specific directions and maintenance intervals in grid form. It will tell you how to maintain your generator and allow you to record things like running hours and maintenance performed. You will find that changing the oil, checking the battery/connections, changing an air or oil filter, and visually inspecting your unit's components are typical maintenance requirements. Warranty work, however, must be performed by an authorized Cummins Dealer/Distributor or certified technician.

Select Maintenance Schedules

The handy maintenance schedules below can also be ordered from your Cummins Dealer/Distributor. All maintenance schedules are specially laminated to increase durability and feature grommets that allow attachment to the generator. They also feature periodic service intervals for your model, and a listing of service parts. To obtain parts for other models, see your Onan Dealer/Distributor.

Quiet Diesel Series Maintenance and Parts

For more extensive repairs or peace of mind, feel free to contact your Onan Dealer/Distributor for more information.

What generator checks or procedures should I follow before a vacation trip?

We recommend:

At least one week prior to trip or guest arrival visit your boat, review your Onan Marine Operators Manual, and perform all necessary services (filters, zinc's, belts, etc). Should maintenance be required, depending on the season, local service centers may have a couple days wait for technician availability. When a certified Onan technician is necessary it is recommended to call around to all local Cummins service centers to get the best-scheduled appointment.
Be sure battery is fully charged
Inspect and tighten all hose clamps and fittings; especially exhaust connections
Check all fluid levels and add as necessary or replace fluid, if necessary, for expected operating temperatures
Perform all pre-start checks as outlined in the Operator's Manual verify all through hull valves are open as necessary
Start and run generator set inspecting for visual leaks and odd noises
Make start and stop attempts from all stations
Turn on all loads expected to be operated during trip, being sure not to overload generator. Run generator set for at least 30 minutes under load
Note operational hours and add to expected hours to log on trip. Based on the total hours identify the necessary spare parts required for service based on service intervals outlined in Operator's Manual. Purchase the necessary spares or a cruise kit from your local Onan Dealer/Distributor
Write down phone numbers of service centers located at or near trip destination in the event of unexpected part needs or service is required

What do you recommend for day to day operation of my Onan marine generator set?

Here are some good general tips. You'll find other helpful information in your Operator's Manual which can be viewed online or ordered through your local Onan Dealer/Distributor if you did not receive one with your generator set.

Inspect and clear sea water strainers of debris, do not wait until they clog. Lack of inspection could result in seawater pump impeller damage
Inspect area around generator set to be sure nothing has moved or been knocked loose (rags, cleaning equipment, tools, spare parts, etc.) while underway, that could block air inlet or outlet or damage wires or hoses
Inspect generator set for fluid levels, leaks, and required service intervals based on operational hours and perform any identified maintenance as necessary

How do I prepare my Onan generator set for extended storage?

We recommend:

Read through your Onan Operator's Manual for familiarization as necessary
Start and run the generator set at all stations
Allow generator set to run applying all load available up to rated output
When possible simulate faults to test control operation
Disconnect and the store battery per manufacturer's guidelines - reference BCI (Battery Council International, Chicago IL)
Drain the oil and replace with new, document viscosity
Verify coolant is capable of storage temperatures and adjust as necessary. If coolant is two years old or older drain and replace with mixture capable of storage temperatures Maximum ratio of ethylene glycol to distilled water is 50/50, recommended is 40/60
Remove raw water impeller and store in cool dry place or discard as necessary
Drain and clean sea water side of heat exchanger. Remove any sea growth or debris if excessive scaling is noticed. A professional cleaning may be required by a local Onan service center
Drain water lift muffler
Wipe down, clean, and lightly oil any parts that could rust
Touch up any paint chips or scratches
Document all work performed including load and control tests. Make repairs or note any failures that need to be addressed before returning the unit to service

When returning the generator set to service:

Review document for storage and make repairs if necessary for any failures or issues noted
Be sure battery is fully charged
Inspect and tighten all hose clamps and fittings; especially exhaust connections
Check all fluid levels and add as necessary or replace fluid, if necessary, for expected operating temperatures
Check for presence and tightness of muffler drain plug or install plug if removed for storage
Check for presence and tightness of heat exchanger drain plug or install if removed for storage
Install removed sea water impeller or new impeller if dried out or otherwise damaged, or discarded at storage
Replace fuel filters primary and secondary
Clean or replace all rusted and corroded terminals and wire connections
Clean and inspect generator brushes and slip rings, if equipped
Connect fully charged battery
Perform all pre-start checks as outlined in the Onan Operator's Manual and verify all through hull valves are opened as necessary
Start and run generator set inspecting for visual leaks and odd noises
Make start and stop attempts from all stations
Check and adjust frequency as needed