Cummins Onan Generator Service: What to Do When Dealers Won't Service

The Quick Answer

You're absolutely right to be concerned about this policy affecting resale values. While some Cummins dealerships are implementing a "10-year rule" for RV engines and Onan generators, this isn't a universal company-wide policy. Many independent diesel shops, RV service centers, and even some Cummins distributors will still service older units. The key is finding the right shop and understanding that parts availability, not age alone, should determine serviceability. Your older Onan generator isn't worthless - you just need to expand your service network beyond that particular dealership.

What's Causing This

This policy stems from several business factors at dealership level, not from Cummins corporate. Many dealerships are focusing on warranty work and newer units because they're more profitable and efficient to service. Older engines often require more diagnostic time, obsolete parts research, and specialized knowledge that newer technicians may lack. The dealership you visited likely implemented this rule to streamline operations and reduce liability on complex older systems.

Parts availability plays a major role too. While Cummins and Onan still manufacture many parts for older units, some components become NLA (No Longer Available) over time, though this varies significantly by component type and model. However, aftermarket suppliers often fill these gaps. The 10-year cutoff is arbitrary - many 15-year-old generators are easier to service than some 8-year-old units with known problematic designs.

Insurance and liability concerns also drive these policies. Dealerships worry about comebacks on older equipment where multiple systems might fail simultaneously. They prefer the predictability of newer units under warranty rather than the potential complications of aged equipment with unknown maintenance histories.

Tools You'll Need

To maintain your older Cummins or Onan equipment, you'll need to build relationships with alternative service providers. Start by identifying independent diesel repair shops in your area that specialize in RV applications. Many of these shops have decades of experience with older Cummins engines and welcome the work that dealerships won't touch.

Create a service network that includes mobile RV technicians who often have extensive experience with older generators. These techs frequently carry common parts and can diagnose issues on-site. Also connect with RV salvage yards that specialize in parts for older units - they're invaluable when you need hard-to-find components.

For DIY maintenance, invest in a good digital multimeter, basic hand tools, and the specific service manuals for your engine and generator models. Always ensure proper shutdown and cool-down before maintenance, work in well-ventilated areas to avoid carbon monoxide exposure, and disconnect power sources before electrical work to prevent shock hazards. Online forums and Facebook groups dedicated to your specific Onan or Cummins model are treasure troves of troubleshooting information and parts sources.

Consider joining Good Sam or FMCA for their technical support networks and discounted services. These organizations often have partnerships with shops that welcome older RV equipment and can provide referrals in different regions as you travel.

Step-by-Step Fix

First, document your equipment completely - model numbers, serial numbers, and maintenance history. This information is crucial when dealing with any service provider. Take photos of your engine and generator data plates and keep digital copies accessible. Create a maintenance log showing when services were performed and what parts were replaced.

Next, research and contact independent shops in your area. Call ahead and specifically ask if they service older Cummins/Onan equipment. Many will proudly tell you they specialize in units that dealerships won't touch. Ask about their parts sourcing capabilities and whether they stock common items for your model year.

Build relationships with multiple service providers rather than relying on one. Have a primary shop for major work, a mobile tech for road emergencies, and know which parts suppliers can cross-reference obsolete part numbers to current equivalents. This redundancy ensures you're never completely stuck.

For ongoing maintenance, establish a more frequent service schedule than you might with newer equipment. Older units benefit from more attention to prevent small issues from becoming major problems. Follow manufacturer-recommended oil change intervals or consult your service manual for appropriate intervals, inspect belts and hoses regularly, and address minor issues promptly before they cascade into larger failures.

When to Call a Pro

Call a professional immediately if you experience any fuel system issues, cooling system problems, or electrical faults that could damage other components. Older engines are less forgiving of neglect, and a small problem can quickly become an expensive one. Don't attempt repairs on high-pressure fuel systems or sophisticated electronic controls without proper training.

Seek professional help for any generator issues involving the control panel, voltage regulation, or power transfer systems. These components are interconnected and misdiagnosis can lead to costly damage. Similarly, if your Cummins engine develops timing or injection system problems, these require specialized tools and knowledge that most DIYers don't possess.

Consider professional service for preventive maintenance even if you handle minor repairs yourself. An experienced tech can spot developing problems during routine service and help you prioritize repairs based on safety and cost-effectiveness. They can also advise when it's time to consider replacement versus continued repair, helping protect your investment and safety.