1993 Johnson Evinrude "ET" 9.9 thru 30 Service Manual, P/N 508282, Page 142Get this manual
Thermomelt Stik Procedure 1Install correct test propeller and place engine in test tank
i pellers, twist and remove all spark plug leads
To avoid accidental starting of engine while changing pro-
2Start engine and run at 3000 RPM for at least five minutes3Reduce engine speed to 900 RPM and mark the cylinder head with 1250 (52 C) and 1630 (73 C) Thermomelt Stik4At 900 RPM, the 1250 (52 C) mark should remain liquid and glossyThe 1630 (730 C) mark should remain dull and chalky If the 1250 (52 C) mark does not remain liquid and glossy, troubleshoot the cooling system for causes of overcooling If the 1630 (73 C) mark becomes liquid and glossy, troubleshoot the cooling system for causes of overheating5When the engine speed is increased to 5000 RPM, both 1630 (730 C) marks should remain dull and chalky If the mark becomes liquid and glossy, troubleshoot the cooling system for causes of overheating