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1993 Evinrude 30 hp. Loud rattling or knocking from shaft or lower unit at low speeds only

F

frankoooo

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:confused::confused: I got an old Lund 14' boat recently with this 1993 Evinrude 30 hp. and it has a loud rattling or knocking like it's coming from the shaft or lower unit and may be vibration related, Only does this at low speed acceleration. Normal at idle and at higher speeds... I was told that it may be something with the prop, so I checked it out and prop looks normal but appeared a bit sloppy I torqued it to 10-15 lbs. HAS ANYBODY heard of Prop Knock? Nevertheless I haven't tested it yet, I think I need to be in the water to really test it cause noise seems to go away when reach plane and at higher speeds... The engine itself starts right up and seems very strong...

Please advise?
 
Before you go checking into various aspects of the engine, mechanical and what-have you.... look very closely at the latches that retain the hood to its lower pan. So many rattling problems of engines of all horsepower sizes through the years have been related to the hood latch assemblies.
 
joereeves said:
Before you go checking into various aspects of the engine, mechanical and what-have you.... look very closely at the latches that retain the hood to its lower pan. So many rattling problems of engines of all horsepower sizes through the years have been related to the hood latch assemblies.
Click to expand...
Well the latch locks tight and I did apply pressure to the motor to see if I could find a point to deaden the sound but that result did not occur.
 
It never hurts to have a spare prop and hardware handy. Get another prop with the same pitch and if it cures the issue you have a good spare.
 
I picked up one of these motors ( $100 ) at a dealer.--------Bracket / upper mount broken.----------Too expensive to fix at a busy shop and an impatient well to do owner.------In the short season it is easy to talk folks into a new motor !!---------So check all motor mounts on this motor.----Check bolts holding engine to the exhaust housing.
 
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