1990 Yamaha 150 Locked Up while running.

kbmsound

Seaman
Joined
Feb 28, 2016
Messages
61
So, I took my boat out this past Thursday to the Skyway Bridge fishing, ran great. Went later to the beach for a swim with the kids, ran great. Time to head to the dock, started making a rattling noise so i backed off the throttle and it went away. Tried to throttle up and same noise came back so I put in neutral. Back to forward and the motor just shut off. Wont even turn over now. The started engages but cant move the flywheel not an inch. Luckily i was close to the dock enough to just go with the wind and paddle for a bit. Got it out of the water. Put it forward and reverse and tried to turn at the propeller, Nothing! Put in neutral, nothing. Can't turn it in either direction. Motor has new head covers with gaskets, new water pump, lower gear oil looks good no water. New lower oil seals. No alarms ever came on, and both thermal sensors are brand new. What happened????
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,129
knocking means something banging around to me.
piston or bearing coming apart
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
With the prop is not turning in neutral, I would suspect the lower unit has seized.
 

kbmsound

Seaman
Joined
Feb 28, 2016
Messages
61
With the prop is not turning in neutral, I would suspect the lower unit has seized.

Nope, the lower unit does spin freely in neutral. I may have typed it wrong. When gears are engaged, i can;t turn the motor by hand. When gears disengaged, prop spins freely but motor still won't turn.
 
Last edited:

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Read it wrong then. Still drop the lower unit to be sure.

So I'll have to agree with 99yam40 - Piston or bearing. Whatever has gone, it isn't good. :blue:
 
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