1999 "EE" 90, 115 FFI, 150, 175 V4, V6 FFI Outboards Service Manual, P/N 787024, 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 of Thermomelt Stiks is Stevens Instrument Company[] At least two Thermomelt Stiks or OIVIC Temperature Gun, PIN 772018, 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 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 headsI Note For the following engine operating temperatures and RPM figures to be correct, the inlet water temperature must be 70 10 (21 3)Pyrometer Procedure