1990 88 Johnson will not shift into forward or reverse.

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wcso549

Cadet
Joined
Sep 14, 2013
Messages
6
I have a 1990 88 Johnson that runs great but will no longer shift into forward or reverse. We were on the water yesterday and were moving pretty good and all of the sudden the engine reved very high and we lost forward motion. At first i thought we lost the prop but that wasn't the issue. The shifter/throttle works fine and the linkage in the motor works fine also. I pulled the lower end plug and drained the oil and its a milky grey color which tells me water has gotten inside. Will the oil being milky cause it not to shift into forward or reverse? Any help would be greatly appreciated. Thanks.
 
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Daviet

Fleet Admiral
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Sep 24, 2008
Messages
8,958
Re: 1990 88 Johnson will not shift into forward or reverse.

Welcome to the forum.
If the oil is a little milky the lower unit should still shift.
If you are sure the shift linkage is working properly, check for a defective prop hub.
Did you check the linkage connection where it goes down to the lower unit, under the bottom carb?
 
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boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: 1990 88 Johnson will not shift into forward or reverse.

The worst thing that could have happened is you broke a drive shaft but check all the linkage first.
 
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wcso549

Cadet
Joined
Sep 14, 2013
Messages
6
Re: 1990 88 Johnson will not shift into forward or reverse.

Thanks for yalls advice, I figured out what it was... My prop came apart. The propeller's insides were all gone so the output shaft was spinning but the prop was not. I ordered a new prop already but had a question after ordering it. Is a 12.75 x 21p a good prop for an 18 ft pontoon? Thanks again.
 
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emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1990 88 Johnson will not shift into forward or reverse.

That is not the correct prop pitch. Why not get a prop the same pitch of the original prop? You will probably find a 13 (or 15) is a more ideal prop pitch.
 
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wcso549

Cadet
Joined
Sep 14, 2013
Messages
6
Re: 1990 88 Johnson will not shift into forward or reverse.

I bought the boat used and the motor seperate. This was the prop that came on the motor so I dont know what the original prop was. Im kinda new at this whole boating thing so could you explain what the difference is with the pitches? Thanks
 
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emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1990 88 Johnson will not shift into forward or reverse.

A 21 pitch prop would work on a lightweight planning hull, such as a 15' Glastron. Not a pontoon prop. You need to get the engine into the upper end of the normal rpm operating range, such as 5500 rpm's. If your engine will run WOT at that rpm, you've got the correct prop on the pontoon.
 
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