440 intermediate screeching noise

If you have a clutch fan, check it. When they are about to seize up, they start screeching intermittently.

You say the sound changes or stops when you pull the PCV or the breather. My guess is something with the PCV(plugged breather?) is causing a vacuum on the engine which is leaking through a small opening in a gasket surface(Valve covers?)Laugh if you want but I had a S-Blazer with a screeching rear main seal caused by a PCV system issue. Drove me crazy at first.

I would check out those breathers as well, as long as they are cheapies. Some of them have a very slight crack in the steel flap that may cause a problem like that, and may just need to be opened up a bit with a screwdriver etc.

I sencond the breather PCV double check. If you want to make sure it's not the clutch fan, diso the belt and see if you can wiggle the assembly, then fire it up. If it doesn't squeeeeal it's the clutch.

Yes, clutch fan is old/wiggles but I mentioned all belts were removed and issue still there.

For the heck of it I went out this afternoon, poured in a small bottle of Marvel Mys oil and fired it up, Minus the Breather cap(ds) or the PCV hose/cap. Ran perfectly for ten mins. As soon as i reconnected PCV she began screeching again. Disconnected it and screeching almost went away, revved motor few blips and came back.

Been playing with these 25 years. This is a first for me.

The only time I had a screech I could not find it was a spun bearing, obviously I eventually found it, oil pressure was adequate on the factory oil pressure gauge considering the age/miles on the engine.

^^^^^ What he said!

Your screech is vacuum through somewhere cause your pcv/crankcase venting is plugged... STOP and fix it.. I have seen this before, It is your ONLY problem....

mine was a crack in the cylinder wall,after trying everything,even running it with the timing cover off.it didn't sound like it was that deep in the motor but it was.this was on a 440 I bought that had never been started after it was assembled,machine shop missed something.

Record it and slow it down... I bet it is your car screaming GET...ME...A...HEMI...!

In an absolute bind one time with my Charger, i was forced to buy the only big block i could find locally... a "good" 440 still in its attractive (though completely trashed) 67 Imperial carrying case. The wiring in the Imp had been so mangled that there would be no starting it up before buying it, and the owner could not tell me exactly why it was parked (was selling it for some long lost relative). So i bought it, dumped it in the Charger, crossed my fingers and started it up.

Well... didn't take a second to learn why it had been parked... and i mean aside from the plumes ov blue smoke out the sidepipes. The engine had this absolutely brutal sounding screech. It literally sounded like the crank was trying to scrape its way through the oil pan... sounding exactly like a very slow grinding wheel on sheet metal. We couldn't diagnose it. No dented sheetmetal, nothing loose, no metal in the oil, no hot spots, nothing. I just ended up driving the damn thing, and after a couple weeks the noise had pretty much gone (steadily) away. Man it sure got some looks in the first week though... that noise was LOUD.

That engine burned just too much oil to last more than a few months in the car, but it had served its purpose. I was actually extremely excited to finally get to pull it apart... I'd been anticipating this since the initial start-up. We couldn't find ANY evidence ov grinding/scraping/anything that would cause this noise. The mystery remains... a mystery.

You do have a breather in the other valve cover correct ? If not its sucking air into the engine from else where maybe causing your noise.

The large port at the lower front of the Carb was loaded w/black crap, I shot in bunch of carb cleaner spray n scraped out the build up crud.

Zero noise last couple of days.

Make any sense? Gotta grab my rebuild kits n booklets I loaned to a buddy, i'll remove carb n thoroughly clean it.

Any further thoughts? other than it allegedly screaming "I Want a Hemi". That one was especially helpful.

A few years ago I had just read an article in a magazine about " having enough vents, breathers, and PCV valve " in your valve covers to rid crankcase pressure/vacuum...

Not 2 weeks after this my mechanic friend had a NEWLY rebuilt 454 chevy, that had just been installed in a PU screeching just LIKE YOU , show up at his shop.. My friend is a GREAT mechanic but he was stumped on this one, just getting ready to pull the pan when I showed up.. I am by no means a great diagnostic person, but the article I had read hit me and looky looky, a PCV valve in one valve cover with NO VENTING on the other side at all.. Pulled the OIL FILL RUBBER PLUG on the other side and it was fixed...

Sounds like you have the same problem.......................