High pitch engine screech
Thread Starter
Burning Brakes
Joined: Oct 2008
Posts: 955
Likes: 50
From: Jersey Shore
High pitch engine screech
I did a little work up on my vette this morning (adjusted the valves, and new points on the distributor) and went for a short 5 minute drive to test everything out. Came back, shut it off, and turned it back on about 5 minutes later. When it started, the motor started making a really high pitched sound. It almost sounds like a whistle, kind of like one of those screeching firecrackers, just about as loud too. It sounds like it is coming from the carb, or maybe the distributor. Its definitely coming from the middle/back part of the motor. It doesnt get louder or sound any different at different RPMS either. Any ideas?
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
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Ck for a vacuum leak. Easy to knock a hose loose when working on things.
JIM
JIM
Thread Starter
Burning Brakes
Joined: Oct 2008
Posts: 955
Likes: 50
From: Jersey Shore
The only vacuum line I have is a PCV that goes into the base of the carb. The rest are plugged, and they are all ok. I wouldnt think a vacuum leak could be loud enough to hurt my ears (and I drove around with open sidepipes for a while 
)
)
Melting Slicks
Joined: Apr 2003
Posts: 2,835
Likes: 495
From: Florida
I got that once, it was the carb base gasket being sucked in due to a mismatch between a spreadbore manifold and squarebore carb. So, depending on your setup, a loose carb or failing gasket. Good Luck
Burning Brakes
Joined: Dec 2008
Posts: 971
Likes: 45
From: Middlesex NJ
The real conundrum is that it doesn't get louder or change in sound with different RPM?
Everything in the motor changes speed with RPM, even vacuum, exhaust pressure.
Do you have power steering or electric fans? Trying to think of what would not change with engine RPM.
Maybe you have a friend pulling a prank on you?
You adjusted your valves? You didn't hang one open did you? You say the sound is coming from the carb area? What did you take off to get to the valve covers? Maybe brake booster hose or oneway valve is cracked and whistling. I dunno.
Everything in the motor changes speed with RPM, even vacuum, exhaust pressure.
Do you have power steering or electric fans? Trying to think of what would not change with engine RPM.
Maybe you have a friend pulling a prank on you?
You adjusted your valves? You didn't hang one open did you? You say the sound is coming from the carb area? What did you take off to get to the valve covers? Maybe brake booster hose or oneway valve is cracked and whistling. I dunno.
Thread Starter
Burning Brakes
Joined: Oct 2008
Posts: 955
Likes: 50
From: Jersey Shore
It seems like the only plausible explanation would be some kind of vacuum leak. Ill have to check into that more thoroughly. I forgot to mention that it does die down a bit if i bring the RPMs down to almost stalling (~500).
I dont think its a spun bearing because it has happened before, but not as loud and just went away. Otherwise, the motor runs good.
Good thing I got rid of all the vacuum lines years ago. Id be searching for days to track down this sound
Thanks for the help
I dont think its a spun bearing because it has happened before, but not as loud and just went away. Otherwise, the motor runs good.
Good thing I got rid of all the vacuum lines years ago. Id be searching for days to track down this sound
Thanks for the help
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