Detroit Diesel Troubleshooting Diagrams

The engine cooling system filter and conditioner is a compact bypass type unit with a replaceable spin-on type element. The factory-installed coolant filter is mounted on the gear case cover. ‪

A correctly installed and properly maintained coolant filter and conditioner provides a cleaner engine cooling system, greater heat dissipation, increased engine efficiency through improved heat conductivity and contributes to longer life of engine parts. ‪

The filter provides mechanical filtration by means of a closely packed element through which the coolant passes. Any impurities such as sand and rust particles suspended in the cooling system will be removed by the straining action of the element. The removal of these impurities will contribute to longer water pump life and proper operation of the thermostat. ‪

The filter also serves to condition the coolant by softening the water to minimize scale deposits, maintain an acid-free condition and act as a rust preventive. ‪

The engine cooling fan can be mounted at the front of the engine and is belt driven from the crankshaft pulley.

On most applications, the fan is thermostatically controlled. This fan assembly is designed to regulate the fan speed and maintain an efficient engine coolant temperature regardless of the variations in the engine load or outside air temperature. No adjustment of the thermostatic control is necessary.

The radiator or heat exchanger (or expansion tank) has a pressure control cap with a normally closed valve. The cap is designed to permit a pressure in the cooling system equal to the rating stamped on the top of the cap. A cap with a 9 on the top allows the cooling system to develop 62 kPa (9 lb/in. ² ) before the valve opens. This system pressure raises the boiling point of the coolant and reduces coolant loss. The maximum allowable coolant temperature, regardless of the pressure cap used, is 99 ° C (210 ° F). ‪

At coolant temperatures below approximately 86 – 89 ° C (186 – 193 ° F) for vehicle, industrial, and keel-cooled marine engines or 69 – 73 ° C (156 – 163 ° F) for heat exchanger-cooled marine engines, the thermostat valves remain closed and block the flow of coolant from the engine to the radiator or heat exchanger. During this period, all of the coolant in the system is recirculated through the engine and is directed back to the suction side of the water pump via a bypass tube. As the coolant temperature rises above 86 – 89 ° C (186 – 193 ° F) for vehicle, industrial, and keel-cooled marine engines or 69 — 73 ° C (156 — 163 ° F) for heat exchanger-cooled marine engines, the thermostat valves start to open, restricting the bypass system, and allowing a portion of the coolant to circulate through the radiator or heat exchanger. When the coolant temperature reaches approximately 97 ° C (207 ° F) (or 82 ° C [179 ° F] for heat exchanger-cooled marine engines), the thermostat valves are fully open, the bypass system is blocked off, and the coolant is directed through the radiator or heat exchanger.

Properly operating thermostats are essential for efficient operation of the engine. If the engine operating temperature deviates from the normal range of 86 – 99 ° C (186-210 ° F) (or 69 – 82 ° C [156 — 179 ° F] for heat exchanger-cooled marine engines), inspect and replace the thermostats, if necessary.

The temperature of the engine coolant is controlled by two blocking-type thermostats located in a housing attached to the right side of the cylinder head.

An impeller is pressed on one end of the stainless steel drive shaft. The other end of this shaft has internal threads, and a retaining bolt secures the water pump drive gear to the shaft. Two identical roller bearing assemblies are used to carry the shaft.

A rectangular rubber ring, located in a groove in the water pump housing, seals the water pump to the gear case cover. A smaller rectangular rubber ring, located in a groove in the water pump cover, seals the cover to the water pump housing. Engines built before October, 1989, are equipped with rubber O-ring seals on the water pump housing and cover.

An oil seal is located behind the bearing assemblies, and a unitized, spring-loaded, face-type water seal is used behind the impeller. This seal prevents water from leaking down the shaft and into the gear case. It also prevents lubricating oil from entering the cooling system. The water and oil seals cannot be replaced without removing the water pump from the engine. ‪

The pump bearings are lubricated by splash oil through a passage from the front of the pump housing. ‪

The centrifugal-type water pump circulates the engine coolant through the cylinder block, cylinder head, radiator and the oil cooler.

The pump is mounted on the front of the engine gear case cover on units built prior to 6R037024 and is driven by the water pump drive gear. The water pump drive gear meshes with the bull gear. ‪

An impeller is pressed on one end of the stainless steel drive shaft. The other end of this shaft has internal threads, and a retaining bolt secures the water pump drive gear to the shaft. Two tappered roller bearing assemblies are used to support the shaft.

An O-ring, located in a groove in the water pump housing, seals the water pump to the gear case. An O-ring, located under the water pump cover, seals the cover to the water pump housing. The water pump bearings are lubricated by splash oil through a passage from the front of the pump housing. ‪

An oil seal is located behind the bearing assemblies, and a unitized, spring-loaded, face-type water seal is used behind the impeller. This seal prevents water from leaking down the shaft and into the gear case. It also prevents lubricating oil from entering the cooling system. The water and oil seals cannot be replaced without removing the water pump from the engine. ‪

Series 60 Marine Engine Coolant Flow Schematic

The centrifugal-type water pump circulates the engine coolant through the cooling system. ‪

The pump is mounted on the rear of the gear case on units built after 6R37023, engines and is driven by the water pump drive gear.