Re: changing 1 piston in 1987 evinrude 115
The tl model engine is a 1983. Those engines did not have the expensive combination VRO pump, just the simple, small fuel pump. Both heads have temp switches in them. They go to ground when the head temps reach 212 degrees and either/both can sound the warning horn in the control box. The hot horn silences when the head temps go back down to 175. You can still have an internal cylinder overheat which will not necessarily set off the horn-if the water diverters are missing, out of position or if there is debris in the passage restricting water flow. Check your factory manual for their specific placement. You can have an overheat and still have a strong telltale. The telltale shows the condition of the impeller, but does not indicate whether either of the two thermostats are functioning (opening) properly.
The tl model engine is a 1983. Those engines did not have the expensive combination VRO pump, just the simple, small fuel pump. Both heads have temp switches in them. They go to ground when the head temps reach 212 degrees and either/both can sound the warning horn in the control box. The hot horn silences when the head temps go back down to 175. You can still have an internal cylinder overheat which will not necessarily set off the horn-if the water diverters are missing, out of position or if there is debris in the passage restricting water flow. Check your factory manual for their specific placement. You can have an overheat and still have a strong telltale. The telltale shows the condition of the impeller, but does not indicate whether either of the two thermostats are functioning (opening) properly.