Its a tell-tale, it lets you know water is circulating the cooling system. On that old of a ski, it is a good idea to disconnect EACH hose one at a time and wire out the connector & hose, then air-chuck to ensure its not coagilated. That water should
be overly warm, but not scalding hot. Test your head temp sensor useing the pan
method as described in your shop manual, it should change ohm at 203* appr. Test
your overheat beeper by simply grounding the sensor wire to a head bolt while running or ignition armed. Bill