115 Johnson Overheating

[mekkamaz]

Hello friends, here?s my headache: 1980 115 Johnson, This motor is new to me, and went out one day to test it on my 15 foot boat, and when comig out no wake zone, starting to rev it up, some place around 3000 or above, the alarm went off, idle a little and alarm stops. Do it couple of more times and have the same results. Pee hole coming out water seems ok, but in muffs i can?t see any water coming out except for the center of the prop... Back home do the following:

Remove heads, looking for some obstructions, none found.
Change water pump, complete.
Change thermostat kit.


I?m worried because i used to have other johnson?s and always see more water for hte exhaust ports above, and this one none. even took off thermostats and valves and i feel like water isn?t enough..and pee hole look the same as the old pump.

any ideas? maybe a clogged water passage? where to look?

another thing, with the lower unit down, i just make some test to look for any water loss in the pump, and see water coming off the little hole all housings have near the water outlet and from the shaft. is this right?

I want to be sure all is good b4 i hit water again.

Thanks,..

 

[Jeff_G]

Re: 115 Johnson Overheating

Some X-flows were bad about corrosion under the powerhead leaking water into the exhaust.
Make sure the poppit valves are installed correctly.
The thermostats should be changed or at least checked properly that they are opening at the right time. Some of the salt water motors in my area just refuse to work with thermostats. You don't want to run without them so what to do?
If you are in a moderate climate you can use restrictors. These are stainless steel washers with 1/4" holes. You can use the stainless washer that the powerhead rubber mounts use! Put them in the same rubber gasket as the thermostats and you will never have to change them again. You will need to let the engine warm up before use and they aren't recommended in northern climes.
Check that the restrictors around the cylinders are in place too.
Finally check for leaks in the water tube coming up to the adapter plate from the gearcase.

I am assuming you put a NEW water pump kit in with new gaskets etc. and no water is leaking from the exhaust or cylinder heads.

 

[mekkamaz]

Re: 115 Johnson Overheating

Thanks, Jeff, pump is all new.
Checked for leaks in tube..none.
Head gaskets news, restrictors in place, I run about 10 min on muffs and seems a little bit cool than before, and water came out hot for the center of prop and warm in pee hole. Some water start to splatter for the two big holes at the upper back end, that I asume is right because all j?s do it.

Will take in water and see how it works, but before i do, any other suggestion?
Thanks.-

 

[wilde1j]

Re: 115 Johnson Overheating

If still running hot, drop LU and put a hose to the water tube (remove thermostats first and replace covers). Water should freely pass through the motor and exit mostly in the exhaust. You may have salt and/or debris in the water passages.