Identifying Rod Knock Vs. Lifters
10-16-2007, 11:41 AM
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Identifying Rod Knock Vs. Lifters Is there any solid way of telling where the noise is coming from in an LS1? My motor has been getting louder...and I have been thinking it was a bend pushrod or a lifter going bad. But lately I am worrying its a rod. The noise is a faint jackhammer or clatter at about 2100-2500, and at idle you can hear some clatter. But its not a deep knock like a hammer on the block, its a lightweight sound. Its been getting louder and thats my biggest concern. I dont want to spend time and $$ on the whole top-end if it ends up being a rod bad. I have put a scope on each valvecover and its not all that noisey. I actually hear more of the noise when I put it on the plastic intake..Where do I go from here??..Thanks
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10-16-2007, 12:06 PM
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pull your pushrods and check them... it may be a lifter too. if its a light metallic sound generally thats the valvetrain... deeper clunks are normally bottom end stuff....
10-16-2007, 12:23 PM
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Wouldnt a rod knock be there alot more often? I mean the noises I hear come and go with rpm and temp. They arent even present on the first 30 seconds of startup. Isnt that when you would hear a rod knock the most?.
10-16-2007, 12:34 PM
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in my past, a rod knock gets louder with RPM... and is louder when everything's not oiled, I think from what you are describing, thats not it. I'd point back to the valvetrain somewhere.
10-16-2007, 02:06 PM
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Scope to what though? Like I said...I dont actually hear much at the covers...BUT I do hear it more on the intake itself...at any runner. Would I hear the lifters more through the intake?...
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10-17-2007, 12:58 AM
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check your valve train... all your pushrods... when my engine had a lifter go to **** it was a deeper sound. more random than rythmatic.. and I couldnt tell which side it was from.
10-17-2007, 01:59 AM
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what is your oil pressure after warming up and going down the road what does it get up to in short runs? what is it when it is cool?
as far as the pushrods, not sure that it is relevant to it being a stock cam, they are just weak points that running the car hard causes it to show up, I say weak, but not sure if that is a good term. Everything in these motors is strong, but the valve train in general is a weak spot with a cam in block motor i guess
as far as the pushrods, not sure that it is relevant to it being a stock cam, they are just weak points that running the car hard causes it to show up, I say weak, but not sure if that is a good term. Everything in these motors is strong, but the valve train in general is a weak spot with a cam in block motor i guess
10-17-2007, 11:37 AM
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On my old motor it had made a light ticking noise after it warmed up that i always thought was a lifter or something, but it ended up being a cracked piston 
so you never really know... Have someone else take a listen? post up a sound clip maybe?
so you never really know... Have someone else take a listen? post up a sound clip maybe? 