I have a 2004 4x4 Ranger 4.0 engine.

Recently, I noticed a slight rumbling right at the point of start-up. Almost instantly the noise goes away. When I first heard this slight rumble I turned off the motor and restarted but no noise on second start up.

The noise seems to be coming from engine compartment or perhaps it is something to do with A/C or interior heat. Does anyone in here have any clues as to what this is or perhaps someone has had the same rumbling noise. I would welcome and appreciate any comments.

Thanks in advance!

 

Almost certainly its lack of oil in the head causing valvetrain noise. It goes away when the oil pump pushes oil back into the head to quiet everything down.