Radiator Pressure Cap (008-047)
B3.9 and B5.9 Series Engines
Section 8 - Cooling System - Group 08
An incorrect or malfunctioning cap can result in 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
bricating 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
NOTE: Transmission fluid can also leak into the coolant
through radiator bottom tank transmission oil coolers. Re-
fer to the OEM service manual.
Inspect for Reuse (008-047-007)
Be sure the correct radiator cap is being used. Refer to
Cooling System - Specifications.
Inspect the rubber seal of the pressure cap for damage.
Inspect the radiator fill neck for cracks or other damage.
Refer to the radiator manufacturer for instructions if the fill
neck is damaged.