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Properly Maintaining Vehicles in Storage or Inventory

Written by Fleet, GM

In a well-run fleet, special attention should be paid to the proper maintenance and storage of new vehicles. Extra care and attention to detail should be taken to make sure vehicles that have spent longer times in inventory are put into service with no product issues. These issues could be stall/no start due to improper battery maintenance or vehicle vibration due to tire flat spotting. The list below will assist in keeping the vehicle inventory protected and ready for customer delivery.

Battery Maintenance

Maintain battery charge on vehicles in inventory. At vehicle delivery, test/charge the battery backup (topped off for 20 minutes or less) to make up for any loss of charge that occurred during the vehicle transit time from the assembly plant to the department.

Every 30 days in dealer inventory, test/charge the battery. This step will allow the battery state of charge to be maintained, which will maximize overall battery life. Vehicle batteries that are in inventory for extended amounts of time without being maintained/ charged will see a significant overall reduction in the battery’s service life. Just prior to putting the vehicle in service, test/charge the battery one last time.

Tire Flat-Spotting

All tires, no matter the manufacturer, are susceptible to flat spotting if the vehicle sits on the lot prior to delivery and is not moved or driven for an extended period of time. Flat spots on the tires can cause vibration concerns.

Vibration issues for flat spotting can develop between 30 and 45 days, depending on the tire design, parking surface, and weather conditions. These usually will be gone after allowing the tires to heat up after a few minutes of driving at highway speeds on smooth surface roads.

Vibration issues that develop from allowing the vehicle to sit without being moved/driven for between 45 and 90 days usually will be gone after allowing the tires to heat up after 10 minutes of driving at highway speeds on smooth surface roads.

To minimize flat spotting, tires should be inflated to 44 psi for longer term storage in inventory. While having higher tire pressures during storage has not been proven to eliminate this concern, under inflation has been shown to contribute to its severity, so higher pressure is preferred to lower pressure.

On the average, tires lose 1 psi every 30 days. Additionally, there is a 1 psi loss in pressure for each 10°F drop in air temperature. For example, a tire with 44psi at 60°F would have 35psi after 6 months in inventory at 30°F air temperature.

Vehicles should be moved every 30 days. If vehicles are allowed to sit more than 30 days at a time, more noticeable tire vibrations may be noted. Vibration issues that develop from allowing the vehicle to sit without being moved/driven for more than 90 days may become permanent and would require tire replacement to repair.

When put into service, the tire pressures must be reset to the values on the Tire Pressure Placard for the proper ride, handling and fuel economy.

Tire Pressure Monitoring System

The TPMS is learned at the assembly plant and should not need to be re-learned for delivery unless wheels are replaced or rotated. Vehicles that have been in dealer inventory for extended amounts of time may have a TPMS light on indicating proper tire pressure is required. Properly adjusting all tire air pressures to the recommended levels and driving the vehicle will turn the light off.

Brakes

Extended storage may increase the opportunity for brake noise issues. Vehicle braking systems tend to be self-cleaning while vehicles are in use, preventing any build-up of corrosion on the brake rotor surfaces. It is a good practice if a vehicle needs to be moved (such as to access other vehicles) to drive it once around the block and apply the brakes several times. This practice will not only eliminate the opportunity for rust to build up on the rotors, but may help to minimize flat spotting of tires. Important: Vehicles should be moved and brakes applied every 30 days in order for this practice to remain effective.

At times, more extensive corrosion can cause pulsation due to thickness variation. This usually happens when the vehicle is parked for long periods of time in humid conditions and the braking surface area under the pads corrode at a different rate compared to the rest of the braking surface area. Cleaning up of braking surfaces (burnishing) can be accomplished by 10 to 15 moderate stops from 35 to 40 mph with cooling time between stops.

Windshields and Wiper Blades

Vehicle windshield wipers are exposed to weathering elements as soon as a vehicle is produced. During extended storage, the wiper blades may not function well due to many factors: 1) dirt/debris/dried soap stuck on the blade surface; 2) oxidation of the rubber blade; and 3) the rubber blade may take a “permanent set” from non-use.

It is recommended that the wiper blades be cleaned with a lint-free cloth or paper towel soaked with windshield washer fluid or a mild detergent. You should see significant amounts of dirt being removed on the cloth. Be sure to wash the windshield thoroughly when you clean the blades. Bugs, road grime, sap and a buildup of car wash/wax treatments may additionally cause wiper streaking.

Do not operate the wipers if the vehicle is extremely dirty with gritty or sandy materials, twigs/sticks in the cowl area. This type of debris dragged by the force of the wipers while dry may cause glass scratching.

The interior surfaces of the window glass may appear hazy (due to surface deposits) after a vehicle has sat in a “closed-up” condition for an extended period of time. It is suggested that window washing during the pre-delivery inspection be performed with plain water. Washing by this method increases the amount of time that the windows will stay clean, as cleaners generally leave a film that accelerates the deposition of new dirt.

Fuel/Lubricants/Oil-Life Monitor

As vehicles age while in inventory, the potential for fueling issues increases. Gasoline powered vehicles should not encounter any fuel related issues while being stored for up to one year. Vehicles should have fresh fuel added as needed or if in stock for over one year.

Do not allow vehicles to run out of fuel during idle conditions. Allowing a vehicle to run out of fuel while idling may cause damage to the fuel pump.

The Oil Life Monitor in new GM vehicles will count down as vehicles are started, moved and run for the purpose of battery charging. If vehicles remain in stock for longer periods, steps should be taken. When the vehicle was assembled, the oil life monitor begins counting down the useful life of the oil.

If the Oil Life percentage indicates below 90 percent of the oil life left before vehicle delivery and the vehicle is older than seven months, it is advised that the oil be changed before putting it in service. If the Oil Life Monitor indicates above 90 percent or the vehicle build date is within six months or newer, the vehicle may be put into service without additional action. If a vehicle remains in stock for one year or greater, you should change the vehicle engine oil.

Published in Police Fleet Manager, May/Jun 2014

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