1997 Ford Ranger 4.0 weird engine humming/whining
Hey, folks, please forgive the cross-posting but I found, in my search
for this answer, some posts about Ford Rangers in both groups. I'll
watch both threads for answers.
I've got a 1997 Ford Ranger with the 4.0 liter V-6 with a manual
transmission and it's developed an odd whine from the engine
compartment. It does it while both driving and just sitting at idle in
neutral (makes hitting Sonic embarassing). I've used a
stethoscope-type sound probe to try to isolate the sound and checked
the serpentine belt idler, the A/C compressor (with the A/C off and
on), the P/S pump, the water pump, and the alternator with no luck on
finding the source of the noise. I then checked both valve covers and
the main intake runner (coming from the air filter snorkel) and didn't
locate the sound.
What I finally found was that there are two devices on the driver's
side of the intake plenum (the black plastic-like thing that runs above
the engine, coming from the rubber snorkel to the air filter); one that
is cylindrical with an electric connection on it and one that is flat,
about 2 inches tall by 3 inches long with an electrical connection to
it with three wires.
That last device seems to be the source of the humming/buzzying/whining
noise. It is about 1/2 inch thick (and 2" high by 3" wide, as I
mentioned) and has two small hoses running to the bottom of it and
coming from a tube that connects to the exhaust manifold. I don't know
what it does, but I tried disconnecting the electric connector and that
didn't make any difference in the sound. However, it seems to be the
source of the noise, the best that I can tell.
Has anyone else had any problems like this? Can anyone tell me what
that device is that I'm describing on the driver's-side of the intake
plenum? More importantly, can anybody tell me what to do to get rid of
Thanks in advance.