Variable Coolant Pump
The variable coolant pump has a housing that supports a shaft with an impeller attached to one end and a drive hub at the other. The housing is attached to the front of the cylinder block with the impeller located in a pumping chamber. The variable coolant pump is driven by a pulley attached to the drive hub and driven by the accessory drive belt at engine speed. For additional information, Refer to: ACCESSORY DRIVE
The variable coolant pump has a shroud mechanism which can be used to create zero flow in the engine coolant circuit to enable accelerated engine warm-up. The operation of the shroud is controlled by the Powertrain Control Module (PCM) through a solenoid valve which is attached to the variable coolant pump housing with a screw. The solenoid valve is connected to the PCM through a hardwired connection. When the engine is cold and the engine speed is between 1900 RPM and 4800 RPM, the PCM activates the solenoid valve and the shroud moves to the 'no coolant flow' position. When the engine approaches the operating temperature the PCM deactivates the solenoid valve and the shroud retracts to its base position. This results full coolant flow from the coolant pump to the engine cooling system.