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2014 40HP 4 Stroke Lower Unit Knocking

S

SFC_Holmes

New member
My 40HP Mercury 4 stroke is knocking in the lower unit at idle when in Forward Gear. If I lift the LU out of the water the rpms increase and it runs like it should and you do not hear the knock. When I lower the LU back into the water, as it is being lowered the rpms decrease and the motor sounds as though it will barely run. Any ideas?
 
If engine is rough idling or "chugging" as some people call it..lower will knock as propshaft speeds up/down and causes clutch dog to ratchet.
 
When and how did this problem come on? The story about tilting up and running better could have something to do with fuel/float/running rich. Be care full it doesn't pull the water pump out of the water and damage impeller or get hot.
 
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