6hp Briggs knocking loudly


Old 05-12-05, 05:40 PM
PatRussell's Avatar
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Join Date: Jan 2001
Location: USA
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6hp Briggs knocking loudly

In the middle of mowing my yard late last week my Yard Machines mower (B&S engine) started knocking loudly but continued to run. I have checked the flywheel key but all is fine there and both the flywheel and blade are tight. Is there a way to try and pin this down aside from tearing the whole thing apart.

It's been great grass growing weather here and my neighbors are probably getting ready to mow for me.....maybe I'll wait a few more days.
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Old 05-13-05, 12:16 AM
cheese's Avatar
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Join Date: Jul 2001
Location: USA
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Hello Pat!

Is the engine full of oil? Could the blade be hitting something on the frame? Other than that, a teardown will be the only way to determine the extent of the damage.

Oh, make sure the bolts that mount the engine to the frame are tight.
Old 05-13-05, 04:12 AM
puey61's Avatar
Join Date: Apr 2004
Location: Upstate New York
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With the piston midway in a stroke and with the plug wire disconnected but the plug still in place, take ahold of the blade, rock it back and forth slightly feeling for any slack before you can feel the piston move in the bore. This will take a good knowledgeable feel to decipher. What you're looking for is possible connecting rod wear at the crankpin...the most likely cause of internal knock.
Old 05-16-05, 11:36 PM
Join Date: Jan 2005
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sometimes noise comes from the coil hitting the flywheel. Especially when it keeps running. 12 thou clearance is about normal but when the bolts loosen off the armature rubs and makes a knocking sound. Any filings in the oil?? If not look elsewhwere.


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