Yamaha F150 running bad...

[Gollane224]

Hi Guys!

Went last summer on a drive with my yamaha 150hp engine and on the way back to harbour, the engine started clapping on rpms... Had do slowly sail back 5mph because the clapping in the engine was terrifying me... Has anybody had a problem like this, that if you put some rpms then the engine starts clapping... The sound is like the belt is knocking on the engine hood...
Where should I start looking the problem?

Best regards!

[TownsendsFJR1300]

There is a re-call on the F150 Balancer. Yamaha updated the balancer several times due to issues. The balancer is located forward on the engine, just behind the fuel filter.

I would get a hold of a Yamaha dealer with at least the vin # (don't run it anymore) and see if it has the new balancer. Its a FREE FIX, no matter how old the engine. I've been told it'll do serious damage, sounds like a "washer machine out of balance knocking" when it goes out.

Might take them 45 minutes to change it out. Hopefully your engine didn't sustain any other damage.

BTW, the balancers themselves look like like two, VERY heavy duty crankshafts, gear driven to each other and the engine itself.

Please post the results

[Gollane224]

Maybe I didn't explained it correctly, the sound is not like vibration it's like clapping... Somebody is knocking fast with a hammer. The engine ran beautifully a hour or smth like that, and then suddenly started clapping...

[TownsendsFJR1300]

Has the balancer been updated/replaced?

And no, it shouldn't do what you described. Wether its a bad balancer, damage from the old balancer, it'd help to diagnose, ruling out the most likely first.