hello I have a 99 ford f150 4x4 drive with 4.6 triton it makes this sound at ilde and in drive ilde fine in park once you bring it up to 1500 RPMS you can not hear the sound it makes only at idle I have changed the clutch fan and the ilde pulley still same noise just need to know what it is so I can fix it


thanks in advance

 

I don't know if this will be any help, but if we suspect it is something that the belt drives, temporarily remove the belt and start the engine. Only run it a short time (30 seconds) and see if you can pinpoint the source if you hear it. You might get a check engine lite because the alternator will not be functioning.

 

I only have a check engine light on due to the o2 sensor I tried up loading a video but will not let me I post one on youtube under 4.6 make noise my username


I'll try that thanks