Remove 115 HP Johnson Lower Unit

V

Valzan

Cadet
Joined
Dec 23, 2007
Messages
6
Hi Folks,

I have a 1975 115 Johnson outboard that starts and runs well. After taking it out today I noticed that water is not coming out of the outlets as it was this morning, and that it is running quite a bit hotter than when I pulled it out of the water today. I want to remove the lower unit and replace the water pump impeller. I have separated the lower unit with the exception of the shifting rod. I see that there is a rocker assembly that attaches to the rod under the carbs but I don't see how it is attached and can't imagine getting in there to do anything. What is the trick to this?

Also, where can I get a water pump kit for it and what should I be looking out for.

Thanks for your help,

WayneV
 
E

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Remove 115 HP Johnson Lower Unit

From the starbord side of the engine find the pair of parallel arms with a bolt in the center. Remove the bolt and spread the ends of the pair of arms to release the shift rod.
 
V

Valzan

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Joined
Dec 23, 2007
Messages
6
Re: Remove 115 HP Johnson Lower Unit

Hi DJ,

Thanks for your reply. As I look under the carbs and at the end of the rocker shaft that seems to connect to the vertical shift rod all I see at the point of connection appears to be a horizontal flat headed pin going front to rear. I have a high resolution picture of it if that would be of any help. If so, how do I post it?

Thanks,

Wayne
 
E

ezeke

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Re: Remove 115 HP Johnson Lower Unit

Maybe this will help:
 

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V

Valzan

Cadet
Joined
Dec 23, 2007
Messages
6
Re: Remove 115 HP Johnson Lower Unit

Hi DJ,

Thanks for your reply. As I look under the carbs and at the end of the rocker shaft that seems to connect to the vertical shift rod all I see at the point of connection appears to be a horizontal flat headed pin going front to rear. I have a high resolution picture of it if that would be of any help. If so, how do I post it?

Thanks,

Wayne
 
HighTrim

HighTrim

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10,486
Re: Remove 115 HP Johnson Lower Unit

The pin you speak of is identified in the pic that Ezeke posted. Click the link on DJs last post to learn how to post pics. Good luck.
 
E

ezeke

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Sep 19, 2003
Messages
12,532
Re: Remove 115 HP Johnson Lower Unit

Your description is accurate.

When you remove the pin from the top of the shift rod's barrel connector by spreading the arms of the bellcrank, the shift rod is released.


You cannot spread the arms without removing the screw that forms the fulcrum of the bellcrank.

If you have not already done so, click on my thumbnail to enlarge it.
 

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V

Valzan

Cadet
Joined
Dec 23, 2007
Messages
6
Re: Remove 115 HP Johnson Lower Unit

Hey Fellas,

Got it apart !! Splitting the rocker lever did the trick. Now as I look at the rubber impeller it seems OK and I don't see any debris in the pump area. Water runs through all of the lower ports. I will check that the impeller is seated properly on the drive shaft and that the key is in the key way as it should be. If that all seems ok, where do I look next, thermostat? Is it located in the Tee block that has a hose going to each cylinder head? I wasn't able to force water through the hoses and therefore through the cylinder heads when I disconnected them from the Tee block and I wasn't able to force water back through the Tee block. What should or shouldn't I be able to do here?

Thanks again,

Wayne
 
HighTrim

HighTrim

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Messages
10,486
Re: Remove 115 HP Johnson Lower Unit

I would change the impeller anyways while you have the lower unit down. Inspect the impeller housing walls for signs of wear. Remove the t stats and run compressed air or the garden hose from the water line to the t stat housing, then back down from the t stat housing to the water line. Ensure the water intake area is free of debris. Order new t stats, gaskets, and poppet valves while they are off. When bolting the lu back up, ensure that the water line slides smoothly into the rubber grommet on top of the impeller housing.
 
V

Valzan

Cadet
Joined
Dec 23, 2007
Messages
6
Re: Remove 115 HP Johnson Lower Unit

Thanks for the advice which totally makes sense. Sounds like a few dollars well spent !!!

Wayne
 
V

Valzan

Cadet
Joined
Dec 23, 2007
Messages
6
Re: Remove 115 HP Johnson Lower Unit

Me again,

I found the water pump kit and have it in my iBoats shopping cart but I don't see a thermostat for the exact year 115 HP. Mine is a 1975 and the part listed is for 1979 and later. Please point me in the right direction if there is one.

Thanks, yet again.

Wayne
 
iwombat

iwombat

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Joined
Jul 12, 2006
Messages
3,767
Re: Remove 115 HP Johnson Lower Unit

There is no t-stat for that year. What you will find is a vernatherm. They rarely ever fail, but sometimes it happens. Run the new impeller, and see what happens. If you still have a problem, inspect the vernatherm housing. That assembly can be a real pain, so I wouldn't go after it until you've made sure you need to.
 
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