Intermittent noise from engine
 

Greetings. Quick Hx: I own a 2002 5.4l FX4 Automatic. I am the original owner and the Truck has been and remains in great mechanical condition. My truck has 105K miles - about 20K in hauling livestock in trailers, 1K+ in off-road/hunting. All stock OEM parts.

Issue: I heard for the first time a loud ‘smooth grinding sound’ (not hash ands raspy, but best defined as a whining grind) coming from the front of the engine compartment while the engine was at idle. There is no variation in the volume or pitch whether in P/R/N/D when in idle. Visual inspection – negative.

Both the pitch and volume increase, slightly, on the road. At first I thought this could be a bearing wearing out (idler pulley bearing for example). Then several miles down the road, it stops. I’m doing 45 MPH and the noise just stops. I pull over to see what gave. Cut the engine off, inspected under the hood, and nothing appeared to have changed.

I restarted the engine, the noise returned. I almost detected the pitch of a vacuum leak upon acceleration this time. 4 miles later, noise is gone. Get home, shut off truck, turn the engine back over, and presto – return of the grind.

Last I remember, bearings aren’t an intermittent problem – once they are shot, that’s it.

The truck performed flawlessly despite the noise. No performance degradation was noted. All fluid levels are at spec. At a loss…

RE: Intermittent noise from engine
 

I have that same thing kind of.. it's when I hit the throttle while going above 45mph that I notice it.. I have to take it in for service this coming week. just hit 30k on my 04.. yes yes.. low miles.. but i travel for work and use a rental for that.. so since last july.. i've only put 5k on my truck :)

I have that whine, a vibration on cold idle. that is REALLY annoying.. but i notice the whine, other people don't pick it up. Go figure.