bowman1268

Hi guys I am hoping somebody might have a insight into this noise as it is driving me nuts.

I have the 4.6 and noticed lately that after is has warmed up there is a faint whistle at idle.When you accelerate it climbs in pitch as if it is matching engine speed but is still faint then by 2500 rpm you can't here it till you slow down again.I am trying to pinpoint it's location but it is such a faint sound that with the hood up you can't pin point it for the other engine noise.At first I thought it was a vacuum leak,but now I am wondering if maybe a diode is failing in the alternator.Have any of you guys had this happen to your rig?

Phyer Phyter

Take the belt off and see if the noise is still there. If not then rotate your pulleys by hand see if any feel a little rougher than the rest or noisier. Check your water pump, power strg, idler, alternator etc. If the noise is still there with the belt off have someone plug the exhaust with a rag and listen to the back pressure and see if the noise is there or increased. Try those and see what you get.

rbrais

^^^Good chance it is a pulley going bad. Or possibly the belt.

bowman1268

Well I rebuilt the alternator and installed new bearings in the idler and tensioner.The whistle is still there.I am guessing it is either the pcv tube or the power steering pump at this point.I guess tomorrow I will pull the pcv hose and check it a second time.

bowman1268

well new pcv and iac and power steering check and it is still whistling.It is insane if you roll down a window just the sound of traffic makes it where you can't hear it but windows up it is very noticeable.I am tearing my hair out trying to find this noise.