1977 70hp Evinrude - no gears.

rich158

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Dec 19, 2009
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14
Hi,

I've got a 15ft glastron with a '77 70hp Evinrude. Motor clunks a bit going into forward or reverse sometimes, usually it only happens when the idle is a little high. Presume this is just a slightly worn dog clutch. Anyway, to the issue:

Did something really stupid yesterday avoiding a big power crusier who decided size has right of way (he had a point I didn't want to hit him!). I was at WOT @28-30knots, swerved to avoid him coming out of a bay into the main river, then yanked the throttle level back off the power to deal with his wake. Unfortunately I also managed to grab the clutch button & effectively slammed it into - what used to be reverse. Heard the slightest "chink" from the motor as we launched off his 5-6' wake. Of course, no forward or reverse drive when we landed... My mate didn't even hear the 'chink' is was that quiet.

There was no grinding. Just the single 'chink' noise. Powerhead still runs perfectly & is pumping loads of water so I think the driveshaft, pinion gear & bearing are still intact. Prop spins freely. all the cables from the control box appear to move all the correct parts under the engine cowl.

So my question: Do these motors have a shear pin or other device to prevent reverse gear from being selected when the motor is spinning too fast? Or have I stripped the teeth off the Dog clutch?

Would like to get a few ideas about replacement parts & rebuild time before I speak to a motor mechanic & get totally burnt the week before the holidays.

Thanks in advance.

Rick
 

JB

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45,907
Re: 1977 70hp Evinrude - no gears.

Ahoy, Rich.

Welcome to iboats. :)

My first thought is that the rubber hub in your prop has spun badly.

Second thought is that something in the gearcase is broke, like the attachment of the pinion gear to the driveshaft.
 

bktheking

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Jul 29, 2008
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5,057
Re: 1977 70hp Evinrude - no gears.

Check prop first. Since it doesn't go into forward or reverse the first part I'd guess would be pinion gear, if it went into one gear but not the other I'd say clutch dog but as you say you get nothing. It's a matter of pulling it apart, this is guessing.
 

tashasdaddy

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51,019
Re: 1977 70hp Evinrude - no gears.

take a permanent marker, draw a straight line, to match cotter pin. like the picture. take the boat for a spin, make it do what it is doing. if the lines are still line up, it is not the prop, if misaligned, the hub in the prop has slipped, and need to have a new hub installed by a prop shop, or a new prop.
 

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rich158

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Dec 19, 2009
Messages
14
Re: 1977 70hp Evinrude - no gears.

Thanks to all Who responded. Have found a 2nd hand replacement for less than the price of new replacement gears. Will be swapping them over in the next couple of days then pull the old one apart when I get time in jan (have a couple of weeks off).

Will let you know what I find in there.

Thanks
Rick
 

rich158

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Joined
Dec 19, 2009
Messages
14
Re: 1977 70hp Evinrude - no gears.

take a permanent marker, draw a straight line, to match cotter pin. like the picture. take the boat for a spin, make it do what it is doing. if the lines are still line up, it is not the prop, if misaligned, the hub in the prop has slipped, and need to have a new hub installed by a prop shop, or a new prop.
Hi tashasdaddy, saw your posts about spun hubs in various other threads & checked for that before posting. definitely not a spun hub. Thanks for the tip about how to check for this.
 

rich158

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Dec 19, 2009
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Re: 1977 70hp Evinrude - no gears.

went to remove the lower unit & may have found part of the problem. the shift rod retaining bracket is sheered. That would be the 'chink' i heard. now to find a spare one!
 

rich158

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Dec 19, 2009
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14
Re: 1977 70hp Evinrude - no gears.

have gears again, will see tomorrow if the select is any more clunky than normal. part number 3-318539 was the cause. I think it's called 'gear select lever' a lot cheaper than a new gearbox.
 

rich158

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Dec 19, 2009
Messages
14
Re: 1977 70hp Evinrude - no gears.

reverse gear jumps if the revs get above 2000. I probably took a tooth off the reverse gear itself.

swapped over to the replacement box & forward/reverse work without issue. old box will sit around until I can find a reasonably priced gear set.

it turned out to be an expensive grab of the clutch button!
 
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