1978 johnson 9.9. hp. thermostat location?

[tidechaser 1]

i just yanked the lower unit after having the top of the motor feel too hot with the muffs on it..and almost no water coming out of the tell tale..just a drop here and there. the impeller is shot as it has been sitting for a long time i a ordering the seals on top of the housing and below as they seem weak and there was water in the lower unit..at least very milky fluid.
i also didnt notice water coming out around the prop..just exhaust. i want to replace the thermostat since it has not been done for years i am sure..however according my book it shows it next to the lower spark plug hole..but it looks just like the other 5 bolts on that plate to me..??!!
since it is very old i dont want to yank a bolt and break it.
so i am hoping someone will know where the danged thing is and tell me if it seems i am on the right track with replacing these seals..i did drain the lower end and check the gaskets..they seemed fine..the main thing i noticed is the seal on top of the housing for the water pump seems to be shot..the shaft slips in too easy and i dont see the seal expand.
i am a bit concerned about messing with the one below the plate..but it am guessing it is bad also.
thanks in advance for your thoughts.

 

[boobie]

Re: 1978 johnson 9.9. hp. thermostat location?

You have to pull the water cover on the cyl head to get at the thermostat.

 

[tidechaser 1]

Re: 1978 johnson 9.9. hp. thermostat location?

cool..that is what i was wondering..there is a little bump under the bottom of the cover that i was thinking might be it. i see there are 8 bolts to take out first..i pray they dont snap upon removal.
thanks for the response.

i also saw something on u tube about putting a 15 hp. carb on one and that brings the engine up to 15 hp..i dont want to put any extra strain on the old engine..but considering this is going on my 20 ft. starcraft it would be nice to have the extra power for emergency..mainly i want it for trolling.

 

[gozierdt]

Re: 1978 johnson 9.9. hp. thermostat location?

On this exploded view of the '79 powerhead, the water cover is #6, and the thermostat is #19. There are 8
bolts to take off to remove the water cover. While you have it off, you'll get a good sense of how much the water
passages are blocked, and if further teardown is warranted.

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1978&hp=9.9&model=10854M&manufacturer=Evinrude&section=Cylinder+%26amp%3B+Crankcase

You may need to remove the cowl latch mechanism to get all
the bolts out. That's #43 on this view:

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1978&hp=9.9&model=10854M&manufacturer=Evinrude&section=Motor+Cover

For a ton of information on these motors, visit "LeeRoy's Ramblings", at:

http://www.leeroysramblings.com/#12_OB

Article 31 talks about the thermostat, and also includes all the information about the differences
between 9.9 and 15 hp engines. You can upgrade to the 15 hp carb and get most of the effect
(there are a couple of other differences he mentions), but he also says the 9.9 is a better
trolling motor because of the smaller carb throat.

 

[tidechaser 1]

Re: 1978 johnson 9.9. hp. thermostat location?

On this exploded view of the '79 powerhead, the water cover is #6, and the thermostat is #19. There are 8
bolts to take off to remove the water cover. While you have it off, you'll get a good sense of how much the water
passages are blocked, and if further teardown is warranted.

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1978&hp=9.9&model=10854M&manufacturer=Evinrude?ion=Cylinder+%26amp%3B+Crankcase

You may need to remove the cowl latch mechanism to get all
the bolts out. That's #43 on this view:

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1978&hp=9.9&model=10854M&manufacturer=Evinrude?ion=Motor+Cover

For a ton of information on these motors, visit "LeeRoy's Ramblings", at:

http://www.leeroysramblings.com/#12_OB

Article 31 talks about the thermostat, and also includes all the information about the differences
between 9.9 and 15 hp engines. You can upgrade to the 15 hp carb and get most of the effect
(there are a couple of other differences he mentions), but he also says the 9.9 is a better
trolling motor because of the smaller carb throat.

thanks..i did get the water cover off earlier today and removed the thermostat..found some sand and gunk in the engine,,yikes!
i am going try and back flush it before i put it back together..not too much gunk but the lower unit had a lot of white nasty gunk with some sand it it next to the water pump.
i saw something on u tube about doing the carb swap..but it idles so well now i am not sure if the 15 hp. carb is such a good idea.
i do know since this is going on a 20 ft. boat it will certainly be better for an emergency to get home if the big motor dies..but if it does not idle well enough or sucks fuel trolling i might be sorry.
thanks for the links very much..i am going to check em out now.