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Sonny's-Carwash College™ Tip of the Month

Checking the Fluid Temperature on Power Packs

CarWash College™ Preventive Maintenance Tip of the Month

June 05, 2008
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At CarWash College™ we teach preventive maintenance. This month we are going to talk about a piece of equipment that, as stated in a previous tip, is the work horse of the car wash. The Power Pack. We are going to talk specifically about fluid temperature and what can be affected by the temperature of the fluid. The fluid temperature, if too hot, can cause many of the components in the system to fail prematurely and produce costly repairs to the car wash equipment.

Most Power Packs have a built-in temperature gauge on the unit where the fluid temperature can be checked. Keeping the oil temperature at a constant working level is critical, since excessively hot hydraulic fluid can rob the system of power and decrease efficiency, as well as lower the viscosity of the fluid, resulting in less lubrication. The operating temperature of a power pack should not exceed 180 degrees Fahrenheit. If the unit exceeds the operating temperature of 180 degrees, it can start to weaken the hoses in the system. Most hydraulic hoses in the car wash industry have maximum operating temperatures of 212 degrees Fahrenheit. Most hydraulic motor manufacturers also suggest a maximum operating temperature of 180 degrees Fahrenheit. After that, significant wear to the internals of the motor can occur. So what causes the changes in fluid temperature?

There are several factors that cause fluctuations in the temperature of the fluid. One of the most common problems seen is that the torque settings on the Power Pack allows too much flow to bypass the flow-control valve, allowing the hot fluid to be dumped right back into the system, without having time to cool. The torque setting can be found on the flow-control valve and can be adjusted accordingly in order to adjust the amount of fluid being bypassed. One of the other things that can affect the system is ambient temperature in the equipment room. Ambient temperature is affected by poor circulation of air in the equipment room or over-heating of the air by using heaters without monitoring their temperature output.

The Power Packs, if maintaining the system temperature, will allow longer operational life and reduced operational cost. Some fluids, such as water-based fluids, may require the use of an after-cooler to maintain temperatures in the system. The cost savings from maintaining the operating temperature are huge. They can range from leaks that can shut the car wash down, costing hundreds of dollars, to hydraulic motors costing upwards of $500.00.

Robert Andre is the Director of Classroom Training for CarWash College™. Robert can be reached at For more information about CarWash College™ certification programs, visit or call the registrar's office at 1-866-492-7422.