9.9/15hp Evinrude running hot

[FishinDave]

Hope someone can help/relate. I have a late 80's to early 90's 15hp Evinrude which i understand its the same as a 9.9 It just has a bigger carb. I also know that evinrude and johnson are pretty much the same. With this being said, the motor is running hot. I recently dropped the lower unit and the impeller looked brand new. I lubed the impeller housing just in case the impeller was sticking and while the lower unit was off, I pumped water into the engine backwards to free anything. Ran the motor in a barrel, ran great. Took the motor out on the water and at idle to slow speeds, the water is flowing but it is warm. At higher speeds the water comes out in spurts(fast and slow as if something is clogged, but always flowing however it gets hot and then when i slow back down, it gets warm but not cool like it should be). The block gets hot as well. I have had the motor in brackish water a few times and i always flush it after. All of this happened after taking it out in saltwater for the first time. I took the thermostat out and ran the engine out on the lake once to see if it might be the thermostat. Still Hot hot, flowing but not like normal(in spurts). My next thing that im going to do is remove the ninety that the water comes out of the engine into and run the hose directly into the motor intead to see if anything is getting clogged at the ninety(the hole in the ninety is smaller than the hose that hooks up to it so maybe just the hose will allow more debri out . When i removed the impeller housing, i noticed a real small cut out on the back side of the housing that look like it was manufactured that way but i thought to myself why would they put a little 1/8"lenght by 1/16 hight port hole in the impeller housing where water is being force up to the engine. The little port hole is closest to the back of the boat motor as if it would bleed off into the exhaust. Any help would be greatly appreciated. Thanks Dave

 

[nwcove]

Re: 9.9/15hp Evinrude running hot

sounds like the symptoms of a bad head gasket? what is the "ninety" that you mention?

 

[AlTn]

Re: 9.9/15hp Evinrude running hot

google..leeroysramblings....outboard motor related articles..9.9/15 hp. maintenance and repair...water pump/circulation articles...it may come down to removing the powerhead and physically cleaning the water passages, replacing exhaust gaskets and the upper water tube gasket....this would be a worst case scenario...replacing the wear plate, water pump housing and impeller may be sufficent..it really becomes a trial and retrial exercise sometimes...with the lower unit off have you tried hooking a water hose up to the water tube to determine if it still over heats while the engine is idling?

 

[FishinDave]

Re: 9.9/15hp Evinrude running hot

sounds like the symptoms of a bad head gasket? what is the "ninety" that you mention?

The ninety is the fitting that comes out of the motor. the water travels through it before going into the short rubber hose and then out into the lake. Its plastic. Im not sure but if the head gasket was bad, wouldn't there be leaking or some sign? Thanks for your response.

 

[FishinDave]

Re: 9.9/15hp Evinrude running hot

Have a fishing trip planned Tuesday and my motor is still acting up. The reason i posted this thread was because the water was flowing out of my engine in fast and slow spurts and getting hot. I took the lower unit off again and found that the inner part of the impeller was worn and the nut that the impeller slides over was turning with the drive shaft normally however it was only catching the impeller every once in a while causing the spurts. Replaced the impeller and put everything back together and now water is not coming out of the engine at all. I pulled the lower unit back off to make sure i had the water tube lined up correctly and it is. I can feel a little bit of air coming out of the water overboard tube(tube that returns water to lake from engine). Any suggestions/help is greatly appreciated.

 

[Haffiman]

Re: 9.9/15hp Evinrude running hot

Unfortunately the second thing on those engines to check, after impeller, when cooling problems occurs, is the upper water tube grommet. To get at it, you have to remove the power head.

 

[Beek14]

Re: 9.9/15hp Evinrude running hot

You did say originally that the water was flowing constant when idle right? But intermittent at higher speeds? I would guess your impeller plate is worn. I would put a water pump kit in it. If the plate has any grooves in it, it can cause the pump to not push the water through properly. The impeller isn't always the only issue. And if the plate has never been replaced, then I'm sure it will need to.