351c noise

[pabear89]

I'm pulling out what little hair I have left with this one.

My 351CJ makes a whistlen sound at the front of the head behind the power steering pump bracket.
The noise will appear only after it has warmed up not when it's cold.

I have checked for any vacume leak or crankcase leak by isolating the pvc valve, carb spray over all intake areas and even checked for header gasket leaks and its none of the above.

By using a peice of tubing and tracing the sound, it is right behind the pump bracket at the head near the block and the gasket.
there is no coolant loss or temp changes from running at idle to freeway speeds.

The sound does not change in eather pitch or volume with engine speed changes, it is most noticable at idle and is still there with a rise in rpm but gets drowned out by the noise from the fan.

The only thing that is differant from before is the addition of an alum highflow water pump from stock cast pump.

Now I made sure the head gaskets were on correctly (has tab showing) when i rebuilt it and it runs great.

But I do remember that the coolant passage area of the gasket had small amount of metal showing in the inside where coolant passes.
Could the flowing coolant over this cause the noise like a tuning fork?

As it only appears when it stars reaching operating temp and after the thermostat opens.
Any Ideas DH?
PB

 

[pabear89]

Well the guys on the 335 forum say its the water pump, so looks like a change back to stock.

 

[bnickel]

are you absolutely sure it's not sucking vacuum from the corner of the intake where it meets the head and the valley end rail of the block? i guess it could be that coolant passage like you described but it seems rather unlikely.

 

[stackz]

how are you sure its not the POS power steering pump deflecting the noise through the bracket??

I'd pull the belt off the power steering pump and see if it continues to do it. If it's the water pump then it's probably the snout bearing going bad. with the engine off just loosen the belt and see if the pulley will wobble around at all.

how old is the dizzy?? I've had one make a little whirring noise in the past but it was rpm dependant.

the puzzling thing is you say it doesnt change in pitch with rpm increase which all of the problems mentioned....would.

even a vacuum leak would have a change in pitch as rpm went up. do you have a vacuum gauge hooked up at idle??

oh, pull the fan off and run it without it so you can hear it at higher engine speeds but keep an eye on the temperature lol.

speaking of which....have you checked the fan shroud to see if you might be making ever so slight contact between it and the fan??? I've seen that as well in the past and if it is JUST barely making contact it will give a whistling to scratching noise and due to the fan blades it can deflect it off to another area.

hell, one time the only way we found it was because it caused enough friction to heat up the shroud material and we were like?? why do we smell fiberglass burning until we realize the shroud was the only thing made of fiberglass in the area lol.