1998 Johnson Evinrude "EC" 90, 100C, 105C, 115, 150, 150C, 175 60 deg. LV Service Manual, P/N 520210, Page 152Get this manual
Engine Temperature Check The Markal Thermomelt Stik is heat-sensitive marker that melts on contact with surface of specific temperatureOne source of Thermomelt Stiks is Stevens Instrument Company
At least two Thermomelt Stiks or OMC Temperature Gun, PI 772018, or digital pyrometer should be used to accurately determine the engine's operating temperatures'
The 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 glossy
To achieve accurate and consistent readings, engine temperature must be gauged at the top of each thermostat pocket
To troubleshoot and isolate cooling system problem properly, be sure to test both cylinder heads
INote For the following engine operating temperatures and RPM
figures to be correct, the inlet water temperature must be 70 10 (21 3)Pyrometer Procedure