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4.3 Vortec top end knock

Old 01-09-2019, 05:09 PM
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If the lifter is dying, then the valves are not fully closed, so it may behave similar to a vacuum leak (like hesitation or bogging).

Depending on Your confidence of the LIM gaskets job quality, I would consider getting the lifters out for inspection. You might have some metal debris grinding Your entire engine inside... Did You notice any oil pressure drop together with the knocking effect?
Old 01-09-2019, 06:08 PM
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Originally Posted by ForeverStomp View Post
The only thing I did when the valve covers were off was I checked to see if any rocker nuts came loose which they didnít but I feel as tho I may have snugged them up to much.

You may have snugged them up to much when? They have a proper torque spec, not a guess.
You may have snugged them up to much at the time you did the LIM gaskets?
Or, when you rebuilt the engine.

Again, I'm not sure if you rebuilt the engine or had it rebuilt, if you did, then I'm assuming you know how to properly adjust the valves prior to starting the engine.

If you had the engine built and you're not familiar with the valve train, I hope you didn't snug any rocker arms up this time around with the proper torquing sequence.

Old 01-11-2019, 10:15 PM
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Just an update. Yes I fully built the motor myself. Those rockers r a torque to yield at 20 ft pounds so itís kinda hard to mess up but anyways. Pulled the pushrods out. Had a bent pushrod on cylinder 4 intake side. Still knocked a as I got a new one. Decided to replace that lifter Incase it got messed up however it still knocks a slight amount. I did see if any lifters were broken and all seem to compress and pump oil. But I let them soak in oil and cleaned the bores out with oil. So Iím stumped at this point. Next step it to just replace all lifter again which sucks. Since they r fairly new along with pushrods.
Old 01-11-2019, 10:21 PM
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Push rods just don't just get bent.
Do a compression check to check for a bent valve.
If cyl 4 is low or no compression you prob have a bent valve.
Scenario I see is while you was changing lower intake gasket part of the gasket or A large chunk of carbon or something was missed and left in the intake opening in the head.
First opening of the valve it got lodged in-between the valve and seat holding the valve open.
The first stroke of the piston to TDC the valve was bent by the piston bending the push rod either then or during the next stroke

Last edited by odat; 01-12-2019 at 02:56 AM.
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