Loud Knock After Replacing Intake Manifold

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Buck69

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The amount of oil flow at the rockers is a concern for me. Have you checked the pressure?
Frequency of knock reflects ignition or possible piston/head contact.
(FYI- A bad rod bearing normally only allows piston/head contact between the exhaust and intake strokes. Hopefully not the case)
Fingers crossed for you.
 

tdsunderla

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Did these back fires happen while cranking or running? I'm assuming cranking. There are a lot of possibilities,I,d look at the starter and flex plate. If you damaged the starter drive the starter gear can be bouncing off the flexplate,and of you cracked a flex plate they sound horrible.
Backfire happened right after starting engine and giving it a bit of gas. My wife stared the engine and I watched the flex plate rotate with engine running and it looked like a a nice smooth disc rotating. Sounds smooth starting. If cracked wouldn’t it be a bit wobbly? Also check cylinder pressure with these results 1-115, 2-120, 3-105, 4-120, 5-110, 6-115, 7-115, and 8-110.
 

fast 99

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Haven't read all the replies but suggest borrowing or buying an inspection camera and look in the cylinders. Have seen instances where carbon dropped on the pistons and sticks there. It will cause lots of noise and in 2 cases broke pistons, both were my tow trucks.
 

brooksman9

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Did you remove all the drive belts to isolate any accessories?
 

tdsunderla

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The amount of oil flow at the rockers is a concern for me. Have you checked the pressure?
Frequency of knock reflects ignition or possible piston/head contact.
(FYI- A bad rod bearing normally only allows piston/head contact between the exhaust and intake strokes. Hopefully not the case)
Fingers crossed for you.
Oil pressure running is 60.
 

tdsunderla

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Ok guys. I realized I am missing a small nut (maybe 3/16”x1/4”) from my gasket scraper and now, just now after starting the engine a dozen times, I am picking up what sounds like a small bb sound. It’s not synchronous, but random. Take a listen…
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Ricko1966

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Have you looked at the plugs? Usually if something goes through the combustion chamber,you crack a head into water. Milk shake oil,or you beat up a plug,or you knock a hole in the top of a piston.
 

tdsunderla

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Have you looked at the plugs? Usually if something goes through the combustion chamber,you crack a head into water. Milk shake oil,or you beat up a plug,or you knock a hole in the top of a piston.
Here’s the plugs. Broken one is my fault (socket slipped).
 

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Ricko1966

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Here’s the plugs. Broken one is my fault (socket slipped).
Take a hard look at #3 plug are there any metal particles on the porcelain?
 

GTX63

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Ok guys. I realized I am missing a small nut (maybe 3/16”x1/4”) from my gasket scraper and now, just now after starting the engine a dozen times, I am picking up what sounds like a small bb sound. It’s not synchronous, but random. Take a listen…
xc_hide_links_from_guests_guests_error_hide_media

This is where you stop and confirm. Put everything else to the side. A piece of metal, even tiny, can wreck an engine.
Run the camera thru the cylinders and look for damage. Or just pull the heads now. It is a couple hours and even if you do not find that nut, or debris, you can know what the noise isn't.
 

tdsunderla

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This is where you stop and confirm. Put everything else to the side. A piece of metal, even tiny, can wreck an engine.
Run the camera thru the cylinders and look for damage. Or just pull the heads now. It is a couple hours and even if you do not find that nut, or debris, you can know what the noise isn't.
Going to do just that. Thank you.
 

SquareRoot

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Backfire happened right after starting engine and giving it a bit of gas. My wife stared the engine and I watched the flex plate rotate with engine running and it looked like a a nice smooth disc rotating. Sounds smooth starting. If cracked wouldn’t it be a bit wobbly? Also check cylinder pressure with these results 1-115, 2-120, 3-105, 4-120, 5-110, 6-115, 7-115, and 8-110.
Nope. Flexplate will still run true. Mine cracked between the lightening holes and I still had a hard time seeing it. It causes a tin canning effect.
 

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