LO 11-1 Explain the relationship of cooling system maintenance to total vehicle operating costs

1. Vehicle Uptime and the Cooling System

Vehicle Uptime and the Cooling System

The cooling system may not receive as much interest as other engine systems, but its operation and maintenance are critical to engine durability and reliability. Consider that manufacturer studies report that as much as 40% of all engine maintenance or breakdown is related directly or indirectly to the cooling system, and over 50% of catastrophic engine failures can be attributed to cooling system failure. Less disruptive, but still a nuisance, are water pump failures, where close to 60% of failures can be attributed to preventable seal leakage. Proper cooling system maintenance can easily be neglected unless it is understood that diesel engine cooling systems need specialized attention because of unique heat loads, engine construction features, and combustion characteristics that affect cooling system maintenance practices.

Cooling system technology is growing in sophistication as manufacturers implement new methods to reduce fuel consumption by decreasing the amount of energy lost to the atmosphere when cooling the engine Figure 1. Waste heat recovery systems that reconvert coolant heat to mechanical or electrical energy are one example of this rapidly growing area of heavy-duty (HD) vehicle technology Figure 2. Methods for reducing energy losses to circulating coolant and heat removal are another target area for new strategies aimed to reduce energy consumption contributing to greenhouse gas (GHG) emissions. It is also important to note that cooling systems are not only used by internal combustion engines but also are needed for electric drive vehicles in today’s commercial vehicle chassis. Thermal management systems that remove heat from batteries, fuel cells, and power electronics depend on the circulation of coolant. However, in this chapter, the primary focus is on the function of the diesel engine cooling systems that are examined along with the operation and maintenance of components in the system. A thorough knowledge of the operation and unique features of the diesel cooling system will assist technicians in choosing diagnostic strategies, performing repairs, and making correct recommendations for service and maintenance of this critical engine system.

FIGURE 11-1: The cooling system removes excess heat from the engine and releases it to the atmosphere through the radiator.

FIGURE 11-2: This exhaust-mounted heat exchanger extracts and repurposes normally wasted exhaust heat using engine coolant.