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Knocking noise when in gear on ear muffs?

P

pseudonym

New member
Hi I just bought a 2006 bf40 that is in great condition however when putting it in forward gear using hose and muffs there is a knocking noise. The guy at the shop said it is simply "prop slap" because the motor is not under load. Removing the prop seems to confirm this as when in gear witout the prop there is no noise.
I won't be able to test it in the water under load for about a week yet but was just wondering if anyone has experienced this before as I don't recall my old bf40 ever doing it. Thanks
 
Sorry Johnny, are you saying it should be doing it in neutral and not when it is in gear?? There is no knocking noise when it's in neutral.
 
Oil is being circulated by the moving driveshaft, thus making prop shaft move ever so slightly,thus creating the noise you hear,this is all perfectly normal. I just reread your post,did not realize you had her in gear,the shop was correct
 
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No its a brand new aluminium 3 blade prop. Since first posting I have fitted the motor to my boat and in the water there is no noise whatsoever, just doesn't like not being under load.
 
They all do that at idle in gear with muffs on. It's the play in the prop shaft to drive shaft gears not being in the water to have it to cushion the play. Perfectly normal.
 
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