1990 Johnson Evinrude "ES" Colt/Junior thru 8 Service Manual, P/N 507870, Page 134Get this manual

Engine Temperature CheckAll Models The Markal Thermomelt Stik is heat-sensitive marker that melts on contact with surface of specific temperature One source for Thermomelt Stiks is Stevens Instrument CompanyThe 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
r:jl To achieve accurate and consistent readings, engine temperature must be gauged on the cylinder water jacketFor the following engine operating temperatures and RPM figures to be correctthe inlet water temperature must be 70 10 (21 C) 0

Thermomelt Stile Procedure

Twist and remove spark plug leads before changing propellers to avoid accidental starting of engine
1Install correct test propeller and place engine in test tank2Start engine and run at 3000 RPM for at least five minutes3 Reduce the engine speed to 900 RPM and mark the engine with 100 (38 C) and 163 (73 C) Thermomelt Stik at locations shown in figures:

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives