High Pitch Squeal

[afgunn]

I am noticing a high pitch squeal that comes from under the hood of the 93 below. It also varies with engine speed. If it was a gasser I would say that I have an intake manifold leak but it is a diesel. What say you?! Is there a regulator that bleeds off excess vacuum from the pump? Could it be that the EGR is not sealing well, it IS disconnected and will soon be blocked!

[afgunn]

I will try to pay more attention but this morning I noticed that I did not hear the squeal until the engine warmed up some - close to full operating temperature. Is it possible that this is the EPR forcing exhaust past the EGR? If so, this will be "fixed" soon - the part is on the way!

[DmaxMaverick]

It could be theoretically possible for the EGR/EPR to squeal, highly unlikely. More likely an accessory (water pump, PS pump, A/C compressor, alternator, vac. pump). Remove the belt(s) and try to reproduce. The only "regulator" that bleeds off excess vacuum is a leak. I've never heard a vacuum leak squeal, but a failing vacuum pump can.

[afgunn]

It is the RADIO! Found it by accident. The only thing I can think of that would cause the interferrence with the raido is the alternator since I have no distributor, wires or spark plugs. I guess the condenser on the alternator (if it has one) or the one on the radio has gone bad.

Thanks Dmax. I probably should have said whistle but squeal was the best descriptive thing I could think of at the time. I was not sure how (if?) the vacuum from the vacuum pump was regulated. Thanks again for the info!

[JohnC]

Could be a bad diode, too.

[afgunn]

Yep, thanks.