Kawasaki Ninja Service Manual: Radiator Cap Inspection

• Remove: Radiator Cap (see Coolant Change in the Periodic Maintenance chapter)
• Check the condition of the bottom [A] and top [B] valve seals and valve spring [C].

If any one of them shows visible damage, replace the cap with a new one.

• Install the cap [A] on a cooling system pressure tester [B].

NOTE

Wet the cap sealing surfaces with water or coolant to prevent pressure leaks.

• Watching the pressure gauge, pump the pressure tester to build up the pressure until the relief valve opens: the gauge needle flicks downward. Stop pumping and measure leak time at once. The relief valve must open within the specified range in the table below and the gauge hand must remain within the same range at least 6 seconds.

Radiator Cap Relief Pressure Standard: 112 ∼ 142 kPa (1.14 ∼ 1.45 kgf/cm², 16 ∼ 21 psi)

If the cap can not hold the specified pressure or if it holds too much pressure, replace it with a new one.