Cummins ISX11.9 CM2250 – Service Manual 008-047   Radiator Pressure Cap

WARNING  Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.

Remove the radiator pressure cap.

Inspect the rubber inner seal and the brass outer seal of the pressure cap for damage.

Inspect the radiator or expansion tank fill neck for cracks or other damage.

Refer to the radiator manufacturer’s or OEM service manual if the fill neck is damaged.

Make sure the correct pressure cap is used. Different caps are specified for different pressure systems. Refer to Procedure 018-018 in Section V.

Pressure test the radiator cap to the rated cap pressure.

NOTE: An incorrect or malfunctioning cap can result in the loss of coolant and the engine operating above engine temperature guidelines

The pressure cap must seal within the value printed on the cap, or it must be replaced.

It is recommended to test the cap’s sealing capability while installed on the vehicle.  For those installations where this is not possible, it is acceptable to test the cap off-vehicle using a radiator pressure cap test kit.  Consult your OEM service manual for guidelines and instructions for this check.