1976 75 HP Evinrude Slips at 3000 RPM Staterd Today

k4tdo

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May 20, 2011
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11
Hello all and Happy July 4th. Frist the stas. I have a 1991 Glasport 175 Fish and Ski with a 1976 75 HP Evinrude. (I know its old but it was on the boat when I bought it. Today the wife and I tool the boat to the lake like we have dozens of times. We were running on plane at about 25 MPH or so when we ran over a small tree limb I didn't see ahead. I felt it hit the bottom of the boat at the motor. When I felt the first thump under my feet I droped the throttle to slow and and waited a few seconds to see what we had hit. We saw the stick hehind us about 3 feed long and about the size of a pop can. Seeing no apparent damage I eased her back into forward and away we went agin. To my suprise and heatbreak when we got to about 3000 RPM just bofore we normaly plain out it feels as if the engine slips out of gear. We stopped shut her down restared the engine and it shifted as goos as it always did forward and reverse. So away we go again, at just about 3K she does the same thing again. We had to limp back to the dock at about 2K+- for almost 5 miles. Amn it was a slow trip. Back at the dock she shifts just fine forward and reverse and pills jjust fine to about 3K and slip she goes. No noise at all just like the motor is in nutrel and a lot of RPMs.

Ok so where do I look first? Clutch Dog I am figuring.

Thanks for yur time. Tim

PS I have a Factory Evinrude Service manual and Parts Catalog.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: 1976 75 HP Evinrude Slips at 3000 RPM Staterd Today

No, it is not the clutch dog. First look to see if you have a badly bent propeller. Assuming that's OK, chances are over 99% you have a slipping prop hub. Don't guess, check it. Use the cotter pin in the prop nut as a reference point. Make a mark on the prop itself, aligned with the reference point. Run the motor till you experience the suspected slippage. Stop the motor and check the marks. If they no longer align the hub slipped. Cure is replace the propeller or have the slipping one re-hubbed. That is a prop-shop job, not DIY.

EDIT: Yeah I lnow, this isn't your prop. But the rubber cushion is in all of them. Believe it.
 

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eavega

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Apr 29, 2008
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Re: 1976 75 HP Evinrude Slips at 3000 RPM Staterd Today

First guess would be a spun prop. Put a scribe mark across the hub. Run the engine in the water until you feel it slip, then check the scribe mark. If it has become misaligned, your have spun your prop. Re-hub or replace the prop, and you should be good to go.

Rgds
 

eavega

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Joined
Apr 29, 2008
Messages
1,377
Re: 1976 75 HP Evinrude Slips at 3000 RPM Staterd Today

Listen to F_R and disregard my advice. He knows what he is talking about :D

Rgds
 

k4tdo

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Joined
May 20, 2011
Messages
11
Re: 1976 75 HP Evinrude Slips at 3000 RPM Staterd Today

Sound good guys. It is the original Prop that most likely came on the engine. And no it is not bent at all. Looks perfectly fine I'll try the mark the prop via the cotter key method when I get time this week. Thanks all. Tim
 

F_R

Supreme Mariner
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Jul 7, 2006
Messages
28,195
Re: 1976 75 HP Evinrude Slips at 3000 RPM Staterd Today

Either way of marking it is perfectly fine. My method merely eliminates the necessity of removing the prop to do it. If the hub slips. the shaft rotates and the prop itself doesn't. The nut and cotter pin rotate with the shaft.
 

k4tdo

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Joined
May 20, 2011
Messages
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Re: 1976 75 HP Evinrude Slips at 3000 RPM Staterd Today

Hello all, yesterday evening I finally got time to go back to the lake and do the prop test. I marked the position of the head of the cotter pin on the Propeller itself, and then ran up the lake and back with a lot lighter load than my slippage day. It actually did not slip as bad as before. Got back to the dock and here is what I found. Pic #1. So it is slipping. I attribute the lack of major slippage to about 200 lbs. less weight on the boat.
Now a new question, from the view of Pic #2 is my motor positioned correctly on the boat. It is a Manual tilt.


pic1.jpgpic2.jpg
 
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