Outboard Motor thump when underway

[Flash Wax Man]

Hello Guys,

I have an 18 ft 1988 Angler CC with a 1984 115 Johnson. I have been having a problem lately with the motor thumping when under way. It feels like I hit something in the water and it happens about every two minutes. It does not kick up the engine but its strong enough for my wife to say, Whats that?

It only happens in foward and happens at any speed. It does not do it on the trailer with the muffs on. Could it be something in the lower unit? Any ideas? Thanks.


Joe - Flash Wax man

 

[bogggar1]

Re: Outboard Motor thump when underway

It won't do it on the trailer with the muffs on because it's not under load... it sounds like the dogs in ur lower unit are worn.

 

[tashasdaddy]

Re: Outboard Motor thump when underway

it's either not going all the way in gear. and the dog is slipping. or the teeth of the clutch dog are worn, it's only going to get worse, and one day just not stay in gear at all, and have to come home in reverse, if lucky. time to rebuild the lower unit.

 

[ezeke]

Re: Outboard Motor thump when underway

Before you start pulling anything apart, make sure that your shift cable is set correctly at the engine end.

To do that, with the engine off, put the control in neutral and disconnect the engine end of the cable; Then, verify that the motor is in neutral by spinning the prop; Next, move the control handle to full forward and back to neutral; Finally, adjust the cable to the shift lever using the Cable Trunnion Nut and check for backlash.

When the cable reconnects smoothly and without force then reconnect.

 

[F_R]

Re: Outboard Motor thump when underway

ezeke has a very valid point. If I may just add a comment to it: It is for sure jumping out of gear, rotating one half a turn and slamming back into gear. It is a classic story "sounds like I hit something". Loose, sloppy, worn or out of adjustment linkages and controls can initiate the problem. Once it starts jumping, further damage occurs VERY quickly. Don't fix the damaged clutch dog and gear without making sure the other stuff is right or you'll just be doing it over. It is way too expensive to be doing it twice.