1986 60HP Mercury - Near Top Spark Plug Water Leak

1986 mercury · #1 May 23rd, 2009, 09:23 PM

I have the subject engine and noticed water running out of the drilled and tapped hole right next to the top spark plug. Is there supposed to be something in the threaded hole? I thought there should be but the dealer said there are drill and tap holes all over the engine that do not use anything. His answer did not make sense to me but the skematic does not show this area clearly?
Can someone help me with this as the enghine runs but a small amount of water comes out of the hole? What is the threaded hole for?

crappiejig · #2 May 24th, 2009, 05:27 AM

The hole is for an overheat sensor. As you can see it does not go thru to the water jacket,so water is not leaking from it. Rather,you need to replace your cylinder block cover gasket,real easy job. I know it may appear to be coming from the threaded hole,but unless your powerhead has a crack,not going to happen. Torque 70 inch pounds on those bolts. If you want the sensor,pony up about 85 bucks.

dogtoter · #3 May 24th, 2009, 07:52 AM

Is it possible a previous owner removed the sensor and someone drilled thru the metal to reach the water? I know it sounds crazy. If water really is coming from the threaded hole that was for the heat sensor (and I am not sure this is the threaded hole in question), and you do not have or want a heat sensor, I guess you could just plug the hole w/ a bolt.

Also, on my 40, the rubber pee hole tube attaches to the block above this heat sensor, could that be your source of water?