Re: 1979 Evinrude 115hp
As sparkie mentioned, the only buzzer on that year's engine is for an overheat. Each head has an overheat temp switch. When it senses the temp of the head gets up to 212 degrees, it sets off the warning horn. The horn will shut off when the engine gets back down to 175 degrees. Normal operating temps are in the 140-155 range at idle. If you are getting a horn, the engine is overheating and should be immediately shut down. Check the impeller first for a strong telltale flow. A weak impeller will usually overheat both heads. If only one head is overheating, it may not be the impeller- you may have one of the two thermostats stuck shut-which will cause an overheat at idle on one side of the block.