I heard from a guy at the MB forum that the IC pump should be running for about 20 seconds after shut down of the engine regardless of engine temp. or running time. Is this true? I don't hear the pump running at all after warming the car and then securing the engine.

Thanks ahead of time.

 

OH is that what always sounds like something is left on when i shut the car off??? im not answering your question above im asking another question lol but it sounds like thats what it is

 

I only hear mine at start up, I never noticed it at shut down.

 

Same here never hear it after the car is off.

 

To hear the IC pump, you have to have your ear right next to the location of the pump. That noise you hear at startup is mostlikely the air pump on the left side of engine compartment just aft of the headlight assembly.

If anyone has time, after running your car for a while, secure the engine, then run over to the passenger side wheel well and listen for the pump. It supposedly only runs for 15-20 seconds.