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Engine Noise Diagnostic Help

Mr. Chuck

Well-known member
Joined
Jan 19, 2005
Messages
230
Location
Southern California
Corvette
1981 Two tone silver / dr grey
Two days ago started my 81 350 CI, started normally, but now has what sounds like a noisy valve lifter. Looking hints on how to proceed with trouble shooting to ID cause of the problem.
Noise rate changes with speed of engine, sound light in nature, not like a lower end problem. My thoughts are to pull the valve covers and inspect for loss of oil supply to rockers, etc. Or possibility some other valve train related failure. Had valve / cam replaced done at ~ 50K miles when #3 cam lobe flatten out.
Now have 126K + miles on my baby.

Any words of wisdom?
 
could be worn rocker arms even well worn valve guides will cause noise.Im betting you got another cam goin south.
 
most speed shops & lots of 'normal' parts stores sell (cheap) set of 8 clips that go on rocker arm so u can run (idle) the engine with the rocker cover off...figure out which kid is raising the commotion...a mechanics stethoscope or just a couple foot long piece of heater hose held to ur ear may help'
diassemble the bad guy(s) and first check the pivot ball/rocker socket for damage...if theyre ok u will need to check lobe lift with a dial indicator.
dont expect to see sign of lack of lube
 
Yeah, what they said.
Check to make sure your valve springs are still in one piece too. once you bullseye the source of the noise, it should be fairly evident where the problem is. If in doubt, tear it apart and start inspecting the components for wear.
Cam
Lifters
Pushrods
Rocker arms
Valve guides
Valves
 
Thanks for all the valuable tips, check the areas noted; adjusted the valves / eliminate the leash. Noise still there, finally remembered old trick of using long screw driver to listen for sound within specific areas of the engine when running; found source of noise to be the dist rotor, one mtg screw had come loose & fallen out, allowing center spring contact to drag / catch on the under side of the dist cap as it rotated. Replaced worn / damaged rotor & cap, no more noise.
 

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