1988 Johnson/Evinrude "CC" 40 thru 55 Models Service Manual, Page 160Get this manual
Engine Temperature Check The Markal Thermomelt Stik is heat-sensitive marker that melts on contact with surface of specific temperatureOne source for Thermomelt Sticks is Stevens Instrument CompanyAt least two Thermomelt Stiks or digital pyrometer should be used to accurately determine the engine's operating temperaturesThe Thermomelt Stik mark will appear dull and chalky when the surface marked is below the Stik's rated temperatureWhen the surface exceeds the Stik's rated temperature, the mark will appear liquid and glossyTo achieve accurate and consistent readings, engine temperature must be gauged at the top of cylinder headINotel For the following engine operating temperatures and RPM figures to be correct, the inlet water temperature must be 70 10 (21 C)
Thermomelt Stik Procedure
1Install correct test propeller and place engine in test tank