SLK 230 (170.449) L4-2.3L SC (111.983) (2001)
Auxiliary Water Pump: Description and Operation
Purpose
The coolant circulation pump serves for maintaining a uniform flow of coolant through the heater core even at low engine speeds and in the residual
engine heat utilization mode.
Function in heating mode
The quantity of coolant pumped through the heater core with the engine running depends on the coolant pump. The coolant circulation pump (M13)
ensures that the water flows uniformly without bubbles through the heater core even at low engine speeds. The coolant circulation pump (M13) is
controlled by the pushbutton control module.
Function in residual engine heat utilization mode
The coolant circulation pump (M13) pumps the heated coolant through the heater core when the engine is standing still. When the REST button is
pressed the temperature is controlled by the pushbutton control module (same as with the ignition ON). This switches on the electric motor for the
coolant circulation pump (M13), which drives the impeller via a magnetic clutch.