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Knocking in Gear case

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craigc

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"I'm hearing a knocking in

"I'm hearing a knocking in the mid housing of the gearcase below the engine and above the lower unit. I pulled the lower unit and checked the shaft bearing and didn't find any excessive wear on the bearing or shaft. Can put your ear on cylinder heads and lower unit and not hear it. only mid way, with engine in idle or clutched in. Anyone have some ideas to help me out? Thanks."
 
Looking for something simple f

Looking for something simple first...

Has there been any work done on it to replace the exhaust tubes? Could they have come loose and are banging against the oil pan?

Has any other work been done on the lower side of your engine?

Have you listened on the exhaust tube on the engines starboard side/rear (a big tube about 3 - 4 inches in diameter) Any unusual sounds coming from there?

Have you used a stethoscope or your ear to a screwdriver which is held on various parts of the engine? This can help locate the sound better...sometimes.

How about the motor mounts? Any sound coming from them?

Does the sound vary in loudness when the engine rpms change?

Does the sound vary in pitch when the engine rpms change?
 
"Mike, No work done recently a

"Mike, No work done recently and I have only owned the boat for three months, but very well kept from the previous owner. The knocking increases speed with the rpm, while running in the water, but I haven't checked if it does it in neutral with an increase of rpm. I'll check with the screw driver like you said to help pin point, but by ear it's louder on the port side of the engine. I'll do some checking and post back. Thanks."
 
"Craig,

I have a very simil

"Craig,

I have a very similar noise on my 08 225 but its more like a squeak or chirp that also comes from the midsection and also from the port side. Its had the noise since new and the engine now has close to 200 hours and the noise has gotten louder.

Mech has no idea (seems to not care too much as long as engine is running) but if you ask me it sounds like a bearing or bushing."
 
"Gaff,
I pulled the lower un

"Gaff,
I pulled the lower unit and checked the shaft bearings and the shaft and all look good. seems strange. Lower unit oil was changed and found some very fine filings in the oil, not unusual. No shavings or bits of metal. It may get to the point of pulling the midsection apart, it might be the Exhaust system like Mike had said. I'll let you know what I find, it might help you find your problem as well. Thanks for the input."
 
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