ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 008-047   Radiator Pressure Cap

The system is designed to use a pressure cap to prevent boiling of the coolant.

Different caps are specified for the two recommended systems:

An incorrect or malfunctioning cap can result in the loss of coolant and the engine running hot.

Air in the coolant can result in loss of coolant from the overflow when the aerated coolant is hot. The heated air expands, increasing the pressure in the system, causing the cap to open.

Similarly, coolant can be displaced through the overflow if the head gasket leaks compression gases to the coolant system.

The operating pressure of the cooling system and the lubricating system can result in the mixing of the fluids if there is a leak between the systems such as the head gasket or oil cooler. Refer to Section 7, Lubricating Oil System.

NOTE: Transmission fluid can also leak into the coolant through radiator bottom tank transmission oil coolers.

Be sure the correct radiator cap is being used. Refer to the Cooling System Specifications in Section V.

Inspect the rubber seal of the pressure cap for damage.

Inspect the radiator fill neck for cracks or other damage.

Refer to the equipment manufacturer’s service manual for instructions if the fill neck is damaged.

Pressure-test the radiator cap.

The pressure cap must seal within 14 kPa [2 psi] of the value stated on the cap, or it must be replaced.

Refer to the equipment manufacturer’s service manual for radiator cap test procedure.