Home › Forum › Ask A Member › Evinrude 18hp temp › Re: Evinrude 18hp temp
What year is this engine? Many of the low tension ignition engines that had a funky idle/plug fouling problem were modified a bit to get the temperature up….If you pull off the thermostat cover, you will see a black rubber plug actually blocking the bypass water passage on top of the head….This modification will result in the higher temps you are seeing and the funky water spray….
To me, I would only use the modification on an engine that is idled/trolled extensively in a colder climate. Definitely wouldn’t do this on a Florida motor. So, you might want to remove the rubber plug if it is there to be on the safe side….
If there is no rubber plug present, I would go through the cooling system as Johnny advises, starting with the water pump….