Why would your 1994 Mercury Grand Marquis make a loud buzzing noise after the engine is warmed up and it stops when you accelerate?

Answer 1

I have a 1994 Grand Marquis and the buzzing noise that I hear every once in awhile is the load levelers (rear shock system) filling with air. Maybe this is what you are hearing and it is a coinencedence that it stops when you accelerate My 1994 Grand Marquis does something like that...it's the air intake thing (press the gas pedal, it moves a valve at the end of the overhead cam). That valve can stick open slightly and hum. You may notice the car idles faster when it buzzes. This can be fixed by going over the edge of the valve with fine sand paper.