1998 Johnson Evinrude EC 5 thru 15 HP Four Stroke Service Manual, Page 168Get this manual
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15Inspect valve housing, spring, and valve for excess wear or damage
16Remove oil pan and gasket from powerhead
17Remove two screws retaining thermostat coverCarefully, remove cover and large springDiscard gasket18Remove washer and diaphragm and cup assembly19Remove vernatherm, small spring, and housing