I have a 1975 65hp Merc. There is a Mercury Switch comming off the switch box. The manuel does not mention what this is. Does anybody know what this is and what does it do. Just wondering.
Switch box? Do you mean the remote control box?<br /><br />An obvious guess would be either a start/stop switch, a choke switch or a trim/tilt switch.<br /><br />If you describe it in more detail we may be able to get closer.
No you are correct, it's off the switchbox and it interrupts the ignition should the motor be trimmed up too far or kicked out of the water by hitting something.
I am pretty sure the mercury swith is for powerhead overheat protection. It is connected to the switch box kill terminal (same as ignition kill) so if the powerhead gets to hot the mercury expands closing the circuit to the switchbox killing the motor. I have read if you do not have any spark to all cylinders of your merc and you have a mercury switch you shoud disconnect it from the switchbox to make sure that is not the problem. <br /><br />Well I was close, I like diligaf answer better.
Got a little confused as 'switchbox' refers to one of the electric ignition-components under the cowling, too. <br /><br />Yes, there is a safety mercury-switch for saving the engine under such events.<br /><br />As this effectively kills the motor, the same points can be used for a remote stop-switch or a man-over-board safety switch.
SASS <br /><br />dilligaf has got it right.<br /><br />As you may have guessed the Mercury switch is a kill switch that has liquid mercury inside it.<br /><br />The switch is designed so that when the engine tilts up (so the propeller is out of the water) the mercury flows through the interior of the switch making electrical contact, grounding the ignition. In short it is a kill switch when you run over a log etc.<br /><br />My tether kill switch is wired in to it (on my boat).<br /><br />Regards, <br /><br />Gold Bear
The switch is not used for temperature protection. It will, however, prevent the motor from running should it become defective.<br /><br />The aim for shutting the motor off when tilted is to prevent running when the (cooling) water intake is above water. At the same time prevents overrevving when the prop is lifted out of the water.
<br /><br />Yes, there is a safety mercury-switch for saving the engine under such events.<br /><br />As this effectively kills the motor, the same points can be used for a remote stop-switch or a man-over-board safety switch.
