15 HP Johnson Water Flow

[bging74]

I just bought a 1986 15hp Johnson that has little or no water flow at idle, and minimal<br />flow at high speeds. Do these motors have <br />thermostats? Are impeller problems frequent?<br />Also the manual for says 100:1 oil ratio, and it seems that most other motors require<br />50:1.

 

[Walter]

Re: 15 HP Johnson Water Flow

I used to own a 1985 Johnson 15 h.p. It, too, ran a 100:1 fuel/oil mixture.<br /><br />Replace the raw water pump impeller if you aren't sure when it was last replaced.<br /><br />Walt

 

[Walter]

Re: 15 HP Johnson Water Flow

I should also mention that I used this for a kicker along side my 150 Merc which ran a 50:1 ratio. They both shared a common fuel tank, so the Johnson ran with the 50:1 ratio as well. It didn't burn as cleanly as it could have with 100:1, but it ran fine.<br /><br />Walt

 

[bging74]

Re: 15 HP Johnson Water Flow

Thanks. My dad had a 1981 15hp Johnson when I was growing up, and I'm almost positive that it was 50:1. So, when I read the manual on this 1986 model, and it said 100:1, It really made me wonder.

 

[clanton]

Re: 15 HP Johnson Water Flow

The 100/1 mix was changed to 50/1 mix SB 2162 dated March 1986. There also were letters from OMC about this change in 1989. After you check/replace waterpump check thermostat and sill have pumping problem/overheating. remove powerhead and replace watertube grommet. The grommet shrinks and blocks water passage. Tale tale sign is seal pushed out of waterpump housing.