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Old 10-10-2011
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Icon5 Knocking noise

So I have searched and have come to a conclusion. My truck is knocking, big surprise right? Anywho here is the skinny.

My truck knocks only when warm. Not just coolant warm but oil warm. When the engine is cold it is absolutely silent. The knock is at idle and up to about 3k rpm. At 3k it quiets down. Now when I accelerate and let off at a high rpm it knocks terribly. The sounds seems to be loudest at the rear driverside spark plug.

I have my thoughts, what are yours?
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Old 10-10-2011
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Is the noise at the top of the engine or the bottom?
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Old 10-10-2011
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It's loudest at the spark plug.
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Old 10-12-2011
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Carbon

Sometimes it's as simple as a piece of carbon rattling around on top of the piston. I saw quite a few of those in the late 60's and early 70's, and some people knocked the stuff out by getting the engine fully warmed up and slowly putting a little water into the intake. We poured it slowly down the carburetor, present day you would pull off the snorkel that goes to the air cleaner and use a spray bottle to direct it into the throttle body ( a little at a time, you do not want to hydraulically lock the engine). The water hitting the hot carbon shatters it and it gets blown out the exhaust.
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Old 10-13-2011
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Sounds like two issues, one being a bit of wrist pin slop (a small, soft tick/tap sound) and the other (your high speed noise) probably being carbon buildup. The OHV 4.0 is well known for developing a slight wrist pin noise, there is a TSB on it, but it doesn't affect reliability or longevity. Also, in the day, Ford wasn't doing repairs for that noise. There is also a TSB discussing how to remove the carbon buildup. The preferred solvent for doing this in a thorough and complete manner is PM-3, available at your Ford dealer. When done implementing the TSB, remember to change out the now dirty plugs, oil and filter.

I don't like hearing this, "Now when I accelerate and let off at a high rpm it knocks terribly.". is this at idle or when driving? Is this a different knock?
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Old 10-13-2011
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I've had problems with knock on my '04 as well. Do you think its spark knock or carbon buildup? If I were you I'd start with seafoam, then start replacing the ignition system. Plugs,wires and coil. Thing is you'll probably never know what is causing the noise until you throw some $ at it. Trial by error and process of elimination. I hate mystery noises, Just found that my hood release cable makes a rattlenoise under certain conditions. So I would also check for things like loose heatsheilds around the cats etc. Loud music seems to remedy it as well :)
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Old 10-13-2011
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yup my ohv was really noisy and leaky
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Old 10-13-2011
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I have ran a can of seafoam through the tank. I will be putting it down the intake this weekend. I'll try it with water too. the knock is consistent. I figured it was the wrist pin based on the location of the knock.
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