Win the warranty game

John Baxter | November 02, 2010

Muth points to seals – input and output seals, as well as wheel seals – as particular spots for pre-trip leak checks. “Any sign of wetness at all requires corrective action,” he says. “Failure to do so may result in component failure caused by low lubricant levels, and these types of failures are, in most cases, considered non-warrantable.”

Muth further recommends inspection of “the transmission and axle breather/air vent locations during a pre-trip to make certain that they are clear.” He adds, “Any blockage of the vent will cause the component to pressurize and create lube leakage.”

Both Wood and Allen list proper clutch adjustment as an important item to monitor. “Clutch adjustment is often determined by a certain amount of free travel measured at the clutch pedal in the cab,” Wood says. Even when a clutch is self-adjusting, it’s smart to check free travel to make sure the clutch is staying adjusted. Remember a clutch that’s not properly adjusted is a slippery slope – it causes increasing amounts of wear.

Proper operation

Keeping a warranty in force requires not only maintenance, but also proper operation.

“Always start in a low-enough gear to move the vehicle without using the throttle,” Muth says. “In other words, if you have to slip the clutch or the truck ‘lurches’ to get it moving, the clutch life will be shortened. And remember – clutch wear is always considered non-warrantable.” Starting in high range from a dead stop may damage transmission or driveline components, even when running bobtail. Evidence of improper gear choice would violate warranty terms.

There’s a reason truck drivers are sometimes referred to as “gearjammers.” It’s the job of the driver, not the shift collars, to synchronize mainshaft and gear speeds through proper double-clutching and timing.

“Smooth shifting means that the mechanical clutches are moving in and out of selected gears with no abnormal wear or snubbing,” Muth says. “This type of wear in a transmission is easy to detect in a repair and is, in most cases, considered to be non-warrantable.”

To be safe, Allen says, use the clutch. “Some drivers are not as proficient at shifting as they might think.”

During downhill braking, “over-revving of the engine may cause engine damage,” Correll says. This would include problems with valves or overheads. The governor function of the ECM will keep rpm from going too high under load but not when traveling downhill, even with the engine brake on. Watch the tachometer and control your speed with the engine or service brakes, or shift up if the rpm exceeds the governed speed or recommended maximum rpm, as listed in the owner’s manual.

Letting the engine idle for long periods can also cause severe damage, Correll says. “Excessive idle times can result in stuck valves, damaged clutches, etc.” Stuck valves come from oil sludge, while clutch damage can result from hours of sitting with the transmission gears clattering away.

As for the other kind of “idle” – a spare truck that’s sitting out a poor economy – Correll notes this as another warranty killer. “Failure to exercise inactive units can cause numerous system and component failures,” he says. n


Heed those warning lights

Dashboard warning lights have become especially critical since the introduction of diesel particulate filters because “a check engine light may mean your DPF needs to be cleaned,” says Michael Donnelley of MHC Kenworth. “That’s a critical part of maintenance. And just because you got a warning light the week before, don’t assume a current light is a result of the same problem.”

Failure to clean ash from the DPF on schedule can result in clogging, overheating, and cracking of the expensive ceramic filter portion of the device.

The check engine light could indicate a DPF problem or a number of others. It means you should take the vehicle in and get electronic diagnosis.