Coolant Expansion Tank Cap for SHACMAN F3000 X3000 This coolant expansion tank cap seals the top of the expansion tank (coolant reservoir) on SHACMAN F3000 and X3000 trucks. It holds system pressure steady, lets the coolant expand and contract through the heat cycle, and keeps the reservoir topped up under normal running. The cap is a direct replacement for the factory part. The seal ring seats evenly on the tank neck and the spring loaded relief opens at the set pressure, so
