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HELP boat knocking

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Somehow the cooler was bent where the hose connected. Saw water leaking when we were filling sacs. Tightened it back down started it back up. Seemed fine. Then started running. I should have been watching the temp. I wasn't. I felt a surge after running 1 minute underload. Then looked at my temp and shut it down.

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If you are mechanically inclined there are a couple things to check just to get an initial idea before going to a mechanic (which I would still do). Check the oil and see if there are any signs of water on the dipstick (moisture or a white milky substance). Next pull each spark plug and see if there are any signs of moisture on the plug (wet or is way WAY cleaner than the rest).

I would start here to determine if you have compromised a head gasket or warped a cylinder head. There could be further damage from these failures.

What were you doing when it over heated? Also what did you do for those "couple minutes" while it was over heating? If the answer is anything more than "we turned the engine off and let it cool" that was a bad choice. At minimum the engine may have to be opened up and worst case removed and rebuilt/replaced.

On edit: ignore the questions about what you were doing. My post was being written when you explained how it happened.

Edited by Wayne
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Oil doesn't look milky.

After it blew we let it cool down a bit. Got the hose reconnected and started it up to let the water cool it down. It cooled it down and we idled back in. There was a faint click at that point. I ordered a new cooler and hose and hooked those up today and started it up to see if I could still hear the click. And now there is this large knock.

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One of the most common side effects of running an engine hot, is that the cylinders go oval. This causes the round piston to rub the narrow section of the cylinder. This is often times described as piston slap.

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Silly question, but have yo looked at the raw water pump to make sure the bracket isn't loose or the base is broke?

that pump can rattle around that much... i did replace the hose on it and pushed pretty hard and it seemed flimsy... you really think it could be the pump rattling around? that would be a savior i'll go check fingers crossed but i doubt it is that.

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the hose i used to install was the incorrect hose which could be making this happen.. i didnt use the molded hose. i have that on order after i went to install and saw what it was.. so there is extra pressure on the outlet of the raw water pump.

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I really like this thought it could be the pump. Bc it is loose. While putting the new hose on the pump moved around. I assume this isn't normal.

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It's hard to tell from that video, but every engine I've heard that had a rod knocking did not sound like that. The rod only knocks on the power stroke. That sound more like exhaust. Does the sound change with the throttle (exhaust sounds do)? How's the oil pressure?

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A simple way to isolate the exact location of the noise is to cut a short length of hose pipe a couple of feet long, then hold one end to your ear and move the other end around the engine to determine the location, a bit like a stethoscope. If the sound is internal, using a long screwdriver, press the handle against your ear and the other end against the motor and you will be able to hear the exact location. I usually try and push the Tragus, that triangular piece of skin on front of the ear back and into the ear canal with the handle. It helps with the sound .

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