First start of my '75 455 buick since a decade, everything went smooth and the engine started up immediately. 4 to 5 smooth and well start ups later in the last month, the engine started to make a noise. The guy I'm fixing my car at told me that it may be a loose connecting rod. Is it possible that after 5 smooth start ups, such a problem appears? What are your thoughts? If any one faced such a problem please tell me what have you done with your engine. And guys what are your suggestions? And what the problem may be from? The oil was changed before first start up. Thanks for your help.
What kind of noise, bearing knock? Whats your hot oil pressure? After 10 years or more of sitting, did you pull the distributor and spin the oil pump to make sure its still primed? Just blindly starting it after over 10 years of sitting without making sure the oil pump is primed is asking for trouble.
Well... done nothing of those. Only oil and spark plugs replacing. Haven't checked the oil pump. I don't think it's a bearing knock.
It would help to have a recording of the noises. Is it a deep metal on metal thud, a light hammer tapping, clack-clack or click-click? Does it go away with RPM, get worse with RPM? Comes from top of motor, bottom of motor, front of motor or back of motor? It could be anything from a loose torque converter to a noisy lifter/rocker or something in between. I'd put an oil pressure gauge on it and see what you have first.
I will upload a recording of the noise as soon as I can. The noise come from bottom of motor and get worse with RPM. It's a loud clack-clack. So what you think?
Sounds like #7 rod bearing. Oil Pump should have been filled with petrol jelly and engine primed before startup. Cut the filter open, the clues should be in there.
The problem source is found. It was the timing chain that was a bit damaged and loose. I will replace it and watch for the oil pump.
