1988 30 hp Evinrude slipping under load?

[sburner]

My motor just started slipping when I run into the tide at high speed or with 2 people in boat. By slipping I mean it revs high but I loose power. It also seems to make more of a banging noise in reverse. I marked the prop and I don't think it is slipping. Is it in the lower unit? What should I do next?

 

[tashasdaddy]

Re: 1988 30 hp Evinrude slipping under load?

did you mark the prop, and then put the boat thru the paces. if it did not slip, you have lower unit problems. i think i would borrow a prop before i crack the lower unit to be sure.

 

[samo_ott]

Re: 1988 30 hp Evinrude slipping under load?

And you must remove the prop to mark it on the inside across the hub, that's the only way to do it. Is that how you did it?

 

[sburner]

Re: 1988 30 hp Evinrude slipping under load?

And you must remove the prop to mark it on the inside across the hub, that's the only way to do it. Is that how you did it?

No. That is not the way I marked the prop. Thanks. I will try it again.

 

[samo_ott]

Re: 1988 30 hp Evinrude slipping under load?

There is an inner and outer hub and there's rubber sandwiched between them. You wont see it but it's there. Mark a big black line across the 2 hubs and the rubber and then run it until it slips and then check it again. If the lines do not line up it has slipped. Search on this forum as a pic of the hub has been posted before... it's here somewhere...

 

[JasonAych]

Re: 1988 30 hp Evinrude slipping under load?

Could also be cavitation (surface air getting to prop). Too large of a diameter prop, motor trim to high, or a broken anti-cavitation plate can cause that.

Also the wrong pitch prop can cause slippage as well.

So if the hub is not slipping, which you are checking, you may want to check into cavitation before tearing it apart. Since it just started happening, I'd have to ask; did anything change with the boat. New prop, less load (rear of boat is sitting higher in the water for some reason), is any of the anti-cavitation plate broken off, is the trim of the motor higher for any reason?

Godd luck!