A good and trusted mechanic just did some engine work on my 1993 Pathfinder (replaced water pump and timing belt), and though the engine runs a lot quieter now, there's a mysterious noise that neither of us can identify.
It sounds like a small part such as a washer or piece of crud pinging around inside the engine. We can't zero in on where it's occurring--it seems to be coming from several places, as if it's moving.
One way to make it occur is to rev the throttle, then let go--a couple of seconds later the pinging usually happens.
Could this be due to misfiring? A small part bouncing around? If so, what are could it be bouncing around in?
So many questions....
-Al