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Discussion Starter #1 (Edited)
Engine Knock noise. Need some help.

Have been hearing a slight knocking sound in what I thought was behind the engine, not the engine itself. Had several friends that are mechanics for a living take look and they said it sounded like it wasnt the engine either... well... changed the spark plugs today, and the engine knock is loud and clear now -=/




I am fearing the worst right now, so if anyone has any idea's on what it is, hit me with it. Funny thing is, if you sit and let it idle for a bit, the knock goes away, until you rev the engine up. Is it possible I may have tightened the spark plugs to much and the valves are slapping the spark plug? I used Ford OEM Spark plugs to be sure it wasnt the iridiums I had in it
 

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Head Unicorn
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kinda hard to tell with the video degrading the audio but kinda sounds like a sticking valve, I'd like to hear the exhaust while it was making the noise. Suggestions for you: compression check on all cylinders and if you find a cylinder with low compresion pull the valve cover on that side and watch the valves on that cylinder.

again, the video may be degrading the noise and it may be much more signifigant than it sounds to me. if so it could be a number of things. The one thing that i can tell you is that valve noise in these motors will travel the entire chain and through the crank mimicing rod or main noise. start with the compression and valves. thats my guess.
 

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I would definitely start with a compression check that will tell you a lot. Another thing you could try is taking the serpintine belt off of the engine and running it for a few seconds. That way you could at least eliminate all of the belt drive accessories.
 

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Hard to tell where the sound is coming from in the video. You say it's behind the engine, could it be the throw out bearing? That is, if your cars a manual.
 

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Discussion Starter #6
Brand new throw out bearing. The knocking noise was there before the TOB was replaced, and after it was replaced. I replaced the NGK Iridium plugs I had in the car (only for 6.5 months, maybe 5k miles total) with the Ford OEM plugs and the knocking got worse.

Friend is saying it could be an exhause leak from the manifold, as that would cause some knocking noise, one thing of note, if I let it sit and idle, eventually the knock stops, once I rev it up again, it starts again. Now here is the funny part, if I turn on the AC at full blast, it will immediately stop the knocking noise. I turn the AC off, and the knock doesnt happen again until I rev up the engine. Its the weirdest damn thing I have ever seen.

Also of note, I have zero loss of power whatsoever. She is still driving just as strong as before. And actually the throttle response seems better than before I changed the plugs. But my gas mileage is crap right now too =/
 
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