Yamaha 6 ran aground and runs badly now

[freshwatermodels]

I'm a newbie to outboards since I haven't used ann outboard since the 1960s and they are very different now.

I bought the motor used. Ran great! Very nice motor until........

I ran aground on some sand. Shut the motor down. Got off the shoal. Restarted the motor. Ran but not smooth or as much power.

What are likely things that would cause this? How do I trouble shoot this?

1999 Yamaha 6MSHY
6M8 S 0011506
T


Any assistance would be appreciated.

Jack

[robert graham]

Probably and hopefully no great amount of damage, but check your prop and skeg for damage and repair/replace as required. Lots of folks, myself included, have run up on shoals and sand bars without great damage, depending on speed. Rocks, oyster bars, stumps and logs are less fun to hit than just soft sand. Good Luck!

[freshwatermodels]

Bob,

This was sand and weeds but kinda hard sand. Went thump, thump a few times before I could stop the motor.

Now top speed of engine is lower and seems to run rougher.

Jack

[freshwatermodels]

Is this forum primarily for larger motors?

[robert graham]

These forums are for all boats and motors, but mostly recreational/fishing types...not much tug boats, submarines, destroyers, etc. Take a close look at your prop for broken or bent blades...may need to replace it. Remove prop from shaft and check for weeds wrapped around shaft, check prop shaft to be sure it's not bent from the impact. Good Luck!

[99yam40]

Not much can be affected by hitting prop, might check to make sure flywheel did not try and shear key and throw off timing a little.
Most problems are fuel related, could be just carb needs cleaning

[freshwatermodels]

Not much can be affected by hitting prop, might check to make sure flywheel did not try and shear key and throw off timing a little.
Most problems are fuel related, could be just carb needs cleaning

Thanks 99

Timing is how it acts. Minimal damage to the prop (paint) and it turns freely. Will have to check prop and shaft for run out/bent shaft.

This is one time when I wish it had a shear pin!

Is it reasonable for an amateur to check timing? Does the motor have to be running to check timing?

Jack

[99yam40]

check with timing light hooked to #1 plug wire would be the easiest, or inspect key and slot to make sure they are still lined up

[muskrat1]

Did you by chance knock the hub loose on your prop?

Inside your prop, is a hub assembly. Either an interchangeable hub (flo-torque type) or a press in molded rubber hub.

Your hub might be slipping from the grounding, causing your loss of speed.

I would not suspect a rough running engine, though.

But if the hub is slipping you will see random RPM changes (typically over rev), espcially under load. Once the hub fails 100%, you will not be able to drive it, as the drive shaft will just spin inside the hub, and not turn the prop.

[robert graham]

Did you by chance knock the hub loose on your prop?

Inside your prop, is a hub assembly. Either an interchangeable hub (flo-torque type) or a press in molded rubber hub.

Your hub might be slipping from the grounding, causing your loss of speed.

I would not suspect a rough running engine, though.

But if the hub is slipping you will see random RPM changes (typically over rev), espcially under load. Once the hub fails 100%, you will not be able to drive it, as the drive shaft will just spin inside the hub, and not turn the prop.

My 2nd on this...a spun prop could be a viable reason for "motor not running as strong as before".

[freshwatermodels]

Spun prop? Is this fixable or replace prop?

[robert graham]

Many props are made in 2 pieces, the center hub with the splines, and the outer piece with the blades, they're assembled together with a black rubber bushing type section that can absorb some shock upon a prop strike. The rubber bushing can fail and slip like a clutch in a car. You can mark the inner and outer pieces with a magic marker, run the motor under load, then see if the marks still lign up...if not, then the prop's hub is "spun". Props can be repaired, but for a 6HP motor a new prop would be the best bet...IF it is "spun". Check it out...

[muskrat1]

I did not read it was a 6hp.

Likely, not a flo torque hub, but most likely a vulcanized rubber press in hub.

Any good prop shop, can check the hub with an arbor press. If you spun the hub, it will press out easy. They will walk you through checking it (or should). They can replace hub if it is bad.

Are all the blades the same shape still? I know you said mainly paint damage. You could have bent your blades, which would mess up the pitch. Prop would vibrate, and the bend will make it off balance.

Another easy fix for prop shop. Or try a new prop, and get old one fixed.

Always good to have a spare.