# Johnson 15hp cooling Problems



## tarawa1943 (Apr 4, 2020)

I have a1986 15hp Johnson 20” shaft. Engine wasn’t peeing, but water is coming from pivot point where shift shaft is located. I put a new water pump on it but results are the same. Attached is a picture where water is flowing out of. Stumped

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## fishwhistle (May 26, 2020)

need more info to really diagnose. Start with some 80# mono or weedeater wire and push up into pee hole while idling in trash can


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## lemaymiami (Feb 9, 2007)

Remember that “pee stream” is just an indicator... If it’s clogged or plugged up you still
might be cooling that motor just fine...

That said, you’ll still want to in-clog it. Fishwhistle’s advice is a good starting point.


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## JC Designs (Apr 5, 2020)

Look for water coming from prop and the area circled in red. Also, when running if the cylinder head gets too hot to hold your hand on for more than 10-15 seconds she is running too hot! Judging from the area you circled, my first guess is the water tube is leaking, missing, or not in the powerhead or pump properly.


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## tarawa1943 (Apr 4, 2020)

I will disassemble tomorrow and check everything out. Someone also told me to get genuine pump and impeller parts.


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## tarawa1943 (Apr 4, 2020)

fishwhistle said:


> need more info to really diagnose. Start with some 80# mono or weedeater wire and push up into pee hole while idling in trash can


I did that first.


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## BrownDog (Jun 22, 2019)

JC Designs said:


> Judging from the area you circled, my first guess is the water tube is leaking, missing, or not in the powerhead or pump properly.


It can be easy to miss sliding the brass tube into the pump when reinstalling the lower after a pump service.


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## JC Designs (Apr 5, 2020)

BrownDog said:


> It can be easy to miss sliding the brass tube into the pump when reinstalling the lower after a pump service.


Very, and especially on that particular motor!


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## Seawoods (Feb 4, 2019)

I hope you are able to resolve it based on the suggestions already mentioned. I had this problem on an OMC 9.9 and it tuned out to be the rubber grommet on the top of the water tube. Appears to be a common problem with this model and hard to fix. I often referred to the OMC articles in http://www.eeroysramblings.com
That guy is an expert on this model of omc engines.


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## tarawa1943 (Apr 4, 2020)

I am thinking it’s the tube also. The kit gave me 3 variations of the grommet. I used the short one that duplicated what I took out. Of course, it was acting the same with the old parts. Maybe it never was correct. Maybe that’s why the guy sold it to me. He said it just needed a new impeller. I just changed the impeller on my 8hp Yamaha, so I really didn’t think it was a big deal.


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## tarawa1943 (Apr 4, 2020)

Reading Leeroys Ramblings, I see that the wrong grommet is in the pump. And it was the wrong grommet in the housing that I removed


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## tarawa1943 (Apr 4, 2020)

Here is the scoop.
1) I needed to change out the grommet to the tall tapered one ( for log shaft motor). It looked as if the pipe was just sitting on to smashing it in.
note: that the original was same configuration and doing the same thing. Weak stream.
2) The Big One. I guess when I was assembling it the first time, I turned the shaft CCW and the impeller vanes reversed directions. I made sure that I only turned the shaft CW.
3) I ended up using the old pump set up, as it was an OEM pump.


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## tarawa1943 (Apr 4, 2020)

Water still comes out at the pivot point where shift rod goes through as in my first picture.


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## fishwhistle (May 26, 2020)

hey she's peeing now! Also good catch on the grommet. It's always a pain to get those to mate correctly. My 25hp merc efi has small flow of water come out of that "pivot point" too not sure if it's correct or not on you OMC


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## tarawa1943 (Apr 4, 2020)

I believe it means that the shaft seal or water tube seal is leaking. I bought a new shaft seal yesterday, which means I will have to tear it down again. Iam getting good at that though!


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## tarawa1943 (Apr 4, 2020)

I changed everything out today with an OMC (not aftermarket) pump kit. Got it back together and it pees great. Unfortunately, water still streams from the pivot point. No idea where it is coming from. I am about ready to modify my jack plate and go back to my short shaft Yamaha. I know the leakage is probably not detrimental, but at 68 years old, I can’t afford to get stuck in the water somewhere by myself if something is wrong. Or maybe just go purchase a new outboard.


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## Smackdaddy53 (Dec 31, 2012)

Sounds like the water tube may have a hole on it leaking water into midsection. I have the same motor on my little river boat.


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## tarawa1943 (Apr 4, 2020)

For the time being, I removed the 15hp engine and modified my jack plate to lower the engine another 2” so I can put the 8hp Yamaha back on and use it. I will be purchasing a gasket set for the Johnson 15hp and change the seals and gaskets on the lower power head. I can check for blockages and leaks while I have it off. This should fix my water problems. I could have just ran it as is, but I know my Yamaha won’t leave me stranded.


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## GSSF (May 25, 2013)

tarawa1943 said:


> For the time being, I removed the 15hp engine and modified my jack plate to lower the engine another 2” so I can put the 8hp Yamaha back on and use it. I will be purchasing a gasket set for the Johnson 15hp and change the seals and gaskets on the lower power head. I can check for blockages and leaks while I have it off. This should fix my water problems. I could have just ran it as is, but I know my Yamaha won’t leave me stranded.


I had the same issue with an 8hp Tohatsu, and I solved the problem by running Rydlyme through it. 50/50 diluted and with an aquarium pump to force the solution up through the motor. I removed the lower unit and did it over a bucket. Let it run for 4 hours. I could not believe the junk/gunk/scale that came out of the water jacket.... It was amazing. Never had cooling/water flow issues again.


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