1978 Evinrude 15 hp - Full throttle but no more action!

[Patmark]

So. I was out playing with my Bombard Aerotec 420 and my old 1978 Evinrude 15 hp. Everything felt good, even though I feel it's a bit slow at 14 knots on full throttle.

However, all of a sudden the fun ended, as the engine stopped working at high rev. The engine sounds just as usual, but on high rev it seems to stop being connected to the prop. Works as usual on slow speed. I turned right back and turned it off, however I had to go for a while to get back to my cabin.

So what can this be? Is there some gearbox or something in these that has broken down? I've got a feeling that this will be too expensive to fix...

I'll be happy to dissect the engine if I have at least a little clue what to look for.

 

[fireman57]

Re: 1978 Evinrude 15 hp - Full throttle but no more action!

You probably have a spun prop hub. Take a marker and make a line on the prop to the lower unit. run it a bit and look and see if they have moved. If they don't line up you need your prop rehubbed

 

[OptsyEagle]

Re: 1978 Evinrude 15 hp - Full throttle but no more action!

If the motor just revs up like it is in neutral when you try to run fast but pushes you OK at trolling speeds, then you probably have a spun propeller. As fireman says, you try to make a scribe mark on the surfaces on both sides (so the scribes line up with each other) of the rubber hub of the propeller. Run it again and if the scribes no longer line up ... the prop is spun.

You can ask your dealer how much to re-hub the prop or buy a new one.

 

[Patmark]

Re: 1978 Evinrude 15 hp - Full throttle but no more action!

Aha! How nice to hear that it could be something on the "outside" and not a gearbox etc. Let's hope so even if it's expensive.

So I guess if I find out this is the case, it's not something that is possible to do yourself?

If I need to replace the whole prop, should I change the size or something at the same time, for performance? I feel I should get it up a few knots more when I'm alone in the Aerotec... But perhaps I've got some problems with compression etc too?

Thanks alot for your response!!

 

[fireman57]

Re: 1978 Evinrude 15 hp - Full throttle but no more action!

The problem with changing pitch on props is you have to know exactly what rpms you are turning. If you are happy then keep it the same. You can't change the rubber in the hub yourself. I think our local shop does it for around 30.00.

 

[Patmark]

Re: 1978 Evinrude 15 hp - Full throttle but no more action!

Oh so it can be done at least? Cause I tried to find the spare part and got this:
PROPELLER BUSHING ASSEMBLY Unavailable

Unsure though if that's the part I need. Would be greatly happy if my local shop can do it, although they are a bit hard to work with. So how do I found uout the rpms? I would like to do something to make it go faster, but perhaps the engine has lost compression and is a lost case?

EDIT: Called my local shop to hear what they say. They said if I swap the prop the rubber hub comes with it. Is that right? They also said it would cost like $280. I've seen props online for $50. What should I make of that?