Gear Case Problem ?

[Fish Head]

I have a 20 ft Pontoon boat with a 7ohp Johnson O/B,both 2000. I noticed at 4000 rpm the motor feels like it shakes,and feels like Im going over very small speed bumps. I thought I may have had a rope caught in the prop or was hiiting things in the water but was not. Only does it after 4000rpm. Does this sound like gear case prob. or spun prop? The motor seems to run fine.Would a broken gear tooth create this sensation?<br />Always Thankful for your help.

 

[OBJ]

Re: Gear Case Problem ?

Hi ya' Fish Head...<br /><br />Drain the lower unit and check the lube for any traces/pieces of metal. Put the engine in neutral and spin the prop. Does it look outta kilter? How's tha' prop look? No dings or bends? Do ya' know if the lower unit has been rebuilt for any reason?<br /><br />Failing all the above.....maybe your dropping a cylinder at high end rpm. Let us know what ya' find on the above and we'll go from there.