Name that I-5 noise!

[quattro2@ix.netcom.com]

My 87 4KCSQ seems to be warbling, I guess you could call it that. The noise is coming from the 
front of the motor and seems loudest around just above idle. It is accompanied by a very slight 
whistling sound. The noise really drops off above/below @ 1000 rpm. 

I have VERY recently changed the following (although it made the noise before I did)

timing belt
water pump
tensioner (idler) pulley
cam and crank seals
oil pump gasket

I followed the Bentley and torqued every thing to spec, the timing belt can be twisted 90 
degrees per the manual etc....

It sounds to me like its coming from the water pump or the thermostat housing. Could it be air 
in the cooling system? The car runs fine and does not overheat. 

Any thoughts??

TIA


Bill