clacking/knocking 5.3L
06-14-2017, 11:38 PM
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clacking/knocking 5.3L Hey guys i just picked up a 06 chevy half ton with a 5.3. truck has 60k on it. the motor is not original to the truck. the motor in it now supposedly is .020 over and has a 218-220 cam in it. sounds like it has a cam judging by the idle characteristics. the motor has about 5000 mi. on it since the rebuild. The friend i got it from told me that the motor had a noise that was concerning but apparently it went away. i drove it and it sounded fine. today i started it and after it was warmed up i revved it up to about 4500 rpm and let it settle back down to idle. when i revved it again it made some very loud clacking/knocking noises. oil pressure is 45-50 at idle whether hot or cold and goes up to 65 when revved. the pressure seems to fluctuate 5-10 psi randomly. Keep in mind that the noise comes and goes. Haven't checked the flexplate or torque converter bolts yet but it really sounds like its coming from the motor. Possibly the pickup tube o-ring?
06-17-2017, 03:44 AM
#2
Launching!
My 4.8 did the same thing, the clacking noise would come and go but my oil pressure wouldn't change and there was no metal in oil or oil filter. it turned out to be a lifter collapsing. they weren't that old either. but I changed them and no problems since. good luck brother.
06-21-2017, 03:19 PM
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I went through something similar last year, you have several routes to take here.
You could try to isolate the cylinder with the noise by pulling a single plug at a time and listening if it gets better.
You could disconnect the torque converter and start the engine, this can eliminate the trans/ converter as being the problem. While down there, give a good look at the flexplate to see if its cracked.
Other things could be checked as well, but in my case it was a bent con rod, hopefully its not the same for you.
You could try to isolate the cylinder with the noise by pulling a single plug at a time and listening if it gets better.
You could disconnect the torque converter and start the engine, this can eliminate the trans/ converter as being the problem. While down there, give a good look at the flexplate to see if its cracked.
Other things could be checked as well, but in my case it was a bent con rod, hopefully its not the same for you.