Yamaha 250 lower unit noisey

[94 Chase]

My 1994 250 Yamaha started making a loud clanging noise while cruising today. At first I thought I chipped a piston so I slowed to limp back to port. Traveled 10 miles at a fast idle which kept the noise down. At the dock I discovered the motor was fine as it did not make noise in reverse. Could this be a chipped tooth on only a forward gear? If it was a bearing I don't think it would last 1-1/2 hours or only make noise in forward not reverse. Thanks ahead for any help.

 

[robert graham]

Re: Yamaha 250 lower unit noisey

My 1994 250 Yamaha started making a loud clanging noise while cruising today. At first I thought I chipped a piston so I slowed to limp back to port. Traveled 10 miles at a fast idle which kept the noise down. At the dock I discovered the motor was fine as it did not make noise in reverse. Could this be a chipped tooth on only a forward gear? If it was a bearing I don't think it would last 1-1/2 hours or only make noise in forward not reverse. Thanks ahead for any help.

Remove prop to check for any obvious problems with shaft, prop or lower unit casing, then drain lower unit oil to check for metal particles in oil, then drop lower unit to inspect oil pump, housing, bearings, seals, etc. Check for play in prop shaft. Good Luck!

 

[Bluefish]

Re: Yamaha 250 lower unit noisey

Hard to tell from reading a post but do the above checks but is sounds like the prop shaft bearing remember the force on those bearing will change from forward and reverse (pushing in pulling out)

 

[stylesabu]

Re: Yamaha 250 lower unit noisey

get boat out of the water,take a sample of lower unit lube 1/4 cup.most drain plugs have a magnet on the end if its full of metal you got lower unit problems. if its been a while since you change lower unit ,then just drain whole thing. use a clean drain pan.your hoping not to find any metal.no metal is then it will have to be something else.post picture of drain plug magnet. hope for clean plug

 

[94 Chase]

Re: Yamaha 250 lower unit noisey

Update.... I found a used unit local for a 1997 250 OX66. Does anyone know if this will fit my 1994 saltwater series? I think it will but would hate to make a mistake. they are both 30" shaft size. Thanks again.

get boat out of the water,take a sample of lower unit lube 1/4 cup.most drain plugs have a magnet on the end if its full of metal you got lower unit problems. if its been a while since you change lower unit ,then just drain whole thing. use a clean drain pan.your hoping not to find any metal.no metal is then it will have to be something else.post picture of drain plug magnet. hope for clean plug