1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

Good day,

I have a 15hp Evinrude I picked up last year 2nd hand (no model number sticker so I can't determine the year). The motor runs smoothly when going slow, however as you speed up and the motor reaches a certain speed (about half throttle) it slips into neutral and revs up. If I lower the throttle when the RPMs slow I can feel it re-click into gear and works fine again until accelerating past that middle throttle point again.

I took it apart the lower unit last night and didn't see anything too out of place (though admittedly not a small engine repair guy). One thing I did see however was that the "shifter shaft" (my apologies I don't know the real name of the part - but I mean the shift attached to the forward, reverse, neutral switch which runs the whole way down to the lower unit) was bent towards the bottom. When I looked at the lower unit attachment (where this shaft attaches to the lower unit) it's bend inside of it to. It's not bend enough that I can't have it attached but thought perhaps since up, down, etc. determine what gear it's in - this may be part of my problem.

I checked all the teeth, etc. on any gears I could get to but didn't see any wear or anything on them. Any help or insight on this problem would be greatly appreciated - I can certainly open up any places that need to be checked.

Best regards,
Paul

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

Typically if there is a gear case problem it is usually the clutch dog and the motor will feel like you hit something and the continue and may clunk repeatedly.Usually if the motor simply revs up as the boat actually slows it is the a spun hub in the prop.
Motor will rev at about the same point over and over and re in gauge as you lower the throttle.
You can check the hub by putting a indelible line across the hub and prop, run the boat and recheck if the line is broken.
If the shift is out of adjustment I think the symptoms will be similar to the the worn clutch dog.

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

steelespike said:

Typically if there is a gear case problem it is usually the clutch dog and the motor will feel like you hit something and the continue and may clunk repeatedly.Usually if the motor simply revs up as the boat actually slows it is the a spun hub in the prop.
Motor will rev at about the same point over and over and re in gauge as you lower the throttle.
You can check the hub by putting a indelible line across the hub and prop, run the boat and recheck if the line is broken.
If the shift is out of adjustment I think the symptoms will be similar to the the worn clutch dog.

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Thanks - I'll check that out shortly and report back in. It does sound like you describe as there's no clunking at all.

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

k...a little more info will help to determine a year range for your motor...metal cowl <hood> or fiberglass?...how did you , if you did, remove the lower unit <gearcase>?...did the gearcase come apart at a seam, or did you access it by removing the prop and pulling a bearing which supports the propshaft?

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

AlTn said:

k...a little more info will help to determine a year range for your motor...metal cowl <hood> or fiberglass?...how did you , if you did, remove the lower unit <gearcase>?...did the gearcase come apart at a seam, or did you access it by removing the prop and pulling a bearing which supports the propshaft?

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It's a metal cowl, and the lower unit did in fact come apart at a seam (basically right at the water pump) - however it looks like to get at the real guts of it I'd need to come in from the prop. I did have the prop off as I wanted to put some pressure against the gears to see if I could make them slip (I couldn't).

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

the gearcase housing itself, is the lower part < the skeg > fastened to the upper part with 6 screws?

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

AlTn said:

the gearcase housing itself, is the lower part < the skeg > fastened to the upper part with 6 screws?

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Yes it is.

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

k.. steelespike's post will narrow it down to the spun prop or "other" issue. The site, marineengine.com, has engine diagrams for 50+ years of omc engines. The 1956 15 hp. page 10, and the 1974 15 hp. gearcase group will show you the differences we're speaking of and may help in other areas. If you haven't already found it search for leeroy's ramblings..9.9-15 hp. maintenance and repair for a wealth of info on these engines.

Post back with anything you can determine and any number of folks will advise or opine.

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

It doesn't appear to be a spun prop.

The driveshaft does appear to be bent somewhat though. It was quite a task getting it back together because it just simply wouldn't reach. From doing some additional reading it looks like it's pretty key to have that line up correctly. Do you think that could cause my symptoms above or should I be checking somewhere else first (since it's a $100 part).

Thanks!

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

AlTn said:

k.. steelespike's post will narrow it down to the spun prop or "other" issue. The site, marineengine.com, has engine diagrams for 50+ years of omc engines. The 1956 15 hp. page 10, and the 1974 15 hp. gearcase group will show you the differences we're speaking of and may help in other areas. If you haven't already found it search for leeroy's ramblings..9.9-15 hp. maintenance and repair for a wealth of info on these engines.

Post back with anything you can determine and any number of folks will advise or opine.

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Thanks for the links - it looks like a match on the '74 - which is about what I had figured.

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

Additionally, I have posted two pictures here with a part that I have no clue what it is (sorry if it's something I should know), but it certainly looks like it shouldn't be free floating around there - but again perhaps it should be. Could someone let me know?

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

Grandpa left his corncob pipe?

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

You're missing the whole upper shift detent mechanism. It bolts to the hole that's right there. Look up the part numbers here: Johnson Evinrude Outboard Motor Parts by Year 1955 to 2011 You can likely get 'em cheap from salvage. Missing that stuff will have your motor jumping to neutral, as it's not being 'held' in by the mechanism.

Good luck!

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

kbait said:

You're missing the whole upper shift detent mechanism. It bolts to the hole that's right there. Look up the part numbers here: Johnson Evinrude Outboard Motor Parts by Year 1955 to 2011 You can likely get 'em cheap from salvage. Missing that stuff will have your motor jumping to neutral, as it's not being 'held' in by the mechanism.

Good luck!

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Thank you!!! I thought something didn't look right with that.

One last request, could someone direct me to that part? I have found some "detent" parts but not the one I'm looking for - or even what "area" I should be looking in to find the part on that site. Or perhaps it's called something different?

Thanks again

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

Here's for a '74, but yours looks different. Can you look for a quarter-sized silver welch plug on your powerhead? Should have model/serial number stamped on it. If it's gone, do you have a cd ignition box bolted to the rear of the powerhead (black)? If you do, it's '77 or newer. We'll need to nail down the year to find the correct part numbers.. A pic of the cowling graphics would work too..

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

kbait said:

Here's for a '74, but yours looks different. Can you look for a quarter-sized silver welch plug on your powerhead? Should have model/serial number stamped on it. If it's gone, do you have a cd ignition box bolted to the rear of the powerhead (black)? If you do, it's '77 or newer. We'll need to nail down the year to find the correct part numbers.. A pic of the cowling graphics would work too..

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Sure thing, here's some pictures.

The welch plug number is C7067913 - but from what I can tell it's a replacement part because the original should be an E number.



Thanks

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

Here's from an '84. Parts will fit yours: Evinrude Cylinder & Crankcase Parts for 1985 15hp E15ECOB Outboard Motor

You need #'s 35, 63, 30, 37. Plus 49, 47, and 39. You already have 42 and 27.

In top secret files at beginning of this forum is a listing of salvage yards. Tim's outboard is one of 'em 218-682-2331. They'll likely have all those parts, nice price and quick ship. You can get all the actual part numbers from the listing below the schematic from above.

Good luck!

Re: 1970s (ish) Evinrude 15hp motor slipping into neutral at higher speeds

kbait said:

Here's from an '84. Parts will fit yours: Evinrude Cylinder & Crankcase Parts for 1985 15hp E15ECOB Outboard Motor

You need #'s 35, 63, 30, 37. Plus 49, 47, and 39. You already have 42 and 27.

In top secret files at beginning of this forum is a listing of salvage yards. Tim's outboard is one of 'em 218-682-2331. They'll likely have all those parts, nice price and quick ship. You can get all the actual part numbers from the listing below the schematic from above.

Good luck!

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Really appreciate your help - this is perfect!

Cheers,
Paul