Problem with 1984 Johnson 25hp: plugs get dirty

[kbait]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

Thermostats have a spring setup that expands to allow the valve to open when the water gets warm, and closes the valve when it cools down... keeping the cooling water at a consistent temp. Motor was designed to use this. No electrical connection at all.

In fact, you can test a thermostat by placing it in boiling water. Valve should open almost immediately. Then place in cold water and valve will close almost immediately.

 

[Pascastel]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

Ok, I never checked if there was a thermostat, but I have been told that they removed it. And water is exiting the cooling system all the time ( even when we just started it).
so.. from what I anderstand, to put the thermostat back, I just need to removed the plate near the sparkplugs (maybe 5 to 8 bolts, it's the plate where the cooling water flow near the pistons) and there should be a place to put it, bloking the flow when it's cold, and opening the flow when it's hot.
I just need:
-the thermostat
-the rubber gasket at the end of the termostat.

Maybe I need as well the spring as well ? There is spring pushing on the termostat to have a tight connection between the gasket and the cooling circuit walls ?

Am I right ?

 

[kbait]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

You are right. You'll need parts 19, 20, 57 and 60
go to "boats dot net" and search for your motor, then part group. It'll have a schematic.

 

[Pascastel]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

OK, so .. for the spark plugs, I have found the offical ones L77JC4, but there is no JC6, it's 823J6C. are they the good ones ?
I want to bring a set of both to try on my next trip in mexico.
The J6C have a shorter srew, so it will not go as far inside the motor that the JC4, is it normal ?

 

[AlTn]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

those L77JC4 plugs will serve you well..if you plan on doing a decarb take an extra set with you as the procedure may foul the plugs somewhat....I could never tell that the decarb hurt the plugs, but I can see that it could

 

[Pascastel]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

Ok, I come back in Mexico in a month. I have what I need (JC4 and J6C plugs, seafom, thermostats etc.)... but I have a question...
Will I be able to travel by plane with a can of seafoam-spray in my luggage ??

Thanks

 

[nwcove]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

i dont think you will be able to take a can of flamable liquid on a plane.

 

[99yam40]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

Thermostat acts as a restriction even when opened and needs to be in the motor to force the cooling water to flow properly to all parts of the motor for proper cooling. Otherwise there will be hot spots and cold spots, this is true in all water cooled motors .
If the stat is removed a restrictor would need to be installed to help with this, but the motor may run too cold for proper ignition without the termostat even with a restrictor.

You need to make sure you have the proper prop on this motor for the boat and load you run it with. If the motor is over propped, this maybe another reason the motor is fouling from lugging.

Good oil and fuel on a good running motor should not foul the plugs.

All outboard manufacturers have products for cleaning carbon from motors, check to see what you can find down there locally because they will all be flammable & not able to be carried on plane

 

[Pascastel]

Re: Problem with 1984 Johnson 25hp: plugs get dirty

Hi,
Do you know what size are the bold to remove the plate under which the water is flowing (to have access to the thermostat) ?
I just want to make sure I bring the right key.
Thanks