4HP Mariner revs but looses power

[Salacia]

Hi

I have a mariner 4hp which I am not sure of the age Serial number 09768784 (if that helps) which runs well and takes off to about half throttle then seems to rev highly and loose power. Someone suggested it could be the prop slipping but I have taken that off and can't see any sign of this. Would anyone have any thoughts?
Thanks

 

[emckelvy]

Re: 4HP Mariner revs but looses power

Are you saying the motor just rev's up and keeps revving but you're getting no resulting forward propulsion?

Or is the motor revving up to some point then dying out? Definitely makes a difference in diagnosis.

Regarding prop slippage, a visual inspection may not find the problem.

Mark the center of the prop (the part which is pinned or splined to the propshaft) and make a corresponding mark on the body of the propeller.

Take the motor out and run it until it slips. Then see if the marks are still aligned or have move relative to each other.

If they've moved, the prop is slipping fer sur!

 

[Salacia]

Re: 4HP Mariner revs but looses power

Great thanks for the advice. I hadn't thought of marking it!!!
The outboard continues to rev but there is no forward momentum.
Also I dropped the gear box oil yesterday and there was no sign of wear in the oil. so am thinking it is more likley to be the prop.

Cheers

Rob