My 1990 240 Wagon has been making some pretty strange noise from the front.
It sounds like a loud squeal, a high pitch scream. I can hear this noise on the freeway when I give it some gas or when I release the gas pedal. I can also hear the noise when the car is stopped, in neutral, and I lightly depress the gas pedal.

I have ruled out alternator (I swapped in a spare), water pump (very new), air conditioning and power steering pump ( I drove without them hooked up), and the harmonic balancer. All belts are nice and tight.

Also I think the noise is coming from the intake manifold area. But I can't think of anything that can make this type of noise from that location.

Any ideas?

I am really baffled.

Thank you.