Marlon

It sort of sounds like a big housefly that might be captured underneath a coffee can!?!?! Sort of a deep & constant - BZZZZZZ....Bzzzzzzzzz...BZZZZZZZZ.

Vacum leak?

Car runs great, and I noticed it the morning after I topped up the oil tank by a half-quart to baseline my dipstick reading on level ground. Stick is in the socket tight and the oil filler cap is tight. I DO notice that the metal oil filler cap doesn;t seem to have that smushy tightness you feel when the rubber cap liner is twisted and snugged against the metal filler neck.

Hmmmm....any ideas?

Marlon

Hmmm - good point, will have to look at that a little closer. I took a very long handle screw driver and placed the tip of it on around the alternator and when I 'listened' through the handle the alternator sounded a little rough...

Marlon

I forgot to mention that the sound occurs after the engine has warmed up for several minutes. I doulble check next time to see if it coincides with oil temp stat opening up - but I think it starts before then. It's almost as if a vacum valve were opening up and there was a little leak. But I will not rule out the alternator or fan bearings.

JasonAndreas

Can you record the sound on your computer and post it as an .mp3?

Marlon

Dont' know - it's a very low frequency though and from the passenger side, aft. Not a high pitch - high rpm sound. I flew Naval rotary wing for 22 years and got very accustomed to high frequency buzzing and vibrations. This noies is like: BBuuuuuuuuhhhhh...and it very slightly picks up when I rev the mortor in neutral. Can't hear it while driving - only at idle at a light or stop. It's almost like a noise coming 'from' something instead of a buzzing emanating from something rotational.

Not BZZZZZZZ - No 'zzz' in it.