3.0L LM2 Duramax Diesel Engine Coolant Flow Control Valve For GM 40009179 The LM2 Duramax diesel engines feature an advanced Active Thermal Management (ATM) cooling system designed to optimize fuel economy, performance, and emissions. This Engine Coolant Flow Control Valve plays a critical role by precisely controlling the coolant flow from the water pump, ensuring peak efficiency in all operating conditions. It combines a rotary control valve and a block control valve to independently manage coolant flow during warm-up (split cooling), eliminating the need for a traditional thermostat. The valve directs coolant to critical components such as the turbocharger, EGR system, oil coolers, and heater core to efficiently regulate temperatures. The system also includes a de-gas circuit to remov.
