Poor maintenance practices combined with a careless operator can quickly ruin a diesel engine, resulting in an expensive overhaul. “Neglect and abuse are the largest concerns affecting our industry,” says Joe Urso, Kubota Engine America Corp. “Proper usage and maintenance, per the factory’s workshop manual, will significantly extend an engine’s life expectancy.”

It’s important for operators to understand the machine’s basic systems. “Every engine component has a specific function. Understanding how these components react with varying scenarios is critical if a [problem] surfaces,” says Urso.

It is also the operator’s job to catch minor issues before they become catastrophic failures. This requires watching for any changes in performance.

“Current and historical operating characteristics (symptoms) are vital when measuring an engine’s health,” Urso states. “For example, abnormal noises or changes in fuel or oil consumption may be early symptoms of a potential concern.”

Recognizing such symptoms, along with relevant inquiries and observations, can help to pinpoint problem areas. “Did the operating environment temperature fluctuate recently; is airflow across the radiator hindered; did the application’s workload change; are cooling system leaks visible; is the recommended fluid in use, etc.?” Urso asks. “Symptoms, either obvious or obscure, occasionally require advice from a properly trained technician to correctly diagnose and repair.”

Maintenance equals longevity

Engine life directly correlates to maintenance practices. “There are things you can do to extend life to overhaul quite a bit,” says Zack Ellison, Cummins customer technical support. Take oil selection, for example.

“The only reason oil needs to be changed is because products of combustion get down past the rings and the acids work to neutralize the total base number (TBN),” says Ellison. A 3.0 is the lowest level you want the TBN to drop.

But different oil types offer varying degrees of protection. “There is fleet-spec oil that has just barely enough additives to meet the minimum requirements, but nothing extra,” Ellison notes. Then there are higher quality oils with better additive packages. “It has more margin in it as far as TBN. It has more extreme pressure additives. A lot of times, you get what you pay for with oils.”

Of course, oil doesn’t have to be the best available to provide the needed protection. “A good oil, not a basement bottom oil, can provide just as satisfactory life to overhaul as the real expensive stuff,” says Ellison.

Maintenance program best practices can also influence engine life. Ben Hanks, senior field service representative, John Deere Power Systems, outlines the following practices to consider:

• • Allow an engine to idle prior to shutting down if it has been run hard. This allows the oil and coolant to continue circulating, enabling components to cool.
• • In cold conditions, allow time for the oil to warm up and circulate throughout the engine to provide lubrication.
• • Perform the manufacturer’s recommended checks and inspections per the operator’s manual.

Major failure sources

A diesel engine will generally give indications that an overhaul is due. “The two main things to look for are crankcase blowby and oil consumption,” says Ellison. “Generally, as the cylinder kits wear, the rings wear; you don’t get as good of sealing against the liners.”

Oil consumption will also increase. “Oil consumption can be an indicator of engine health,” says Hanks.

A rule of thumb is 1 quart consumed for every 100 gal. of fuel. Oil consumption less than that is considered normal, while higher consumption rates should be reviewed by an authorized dealer. Oil consumption does change slightly depending upon the season (temperature) and usage (loading), so it’s important to take note of any substantial changes.