Merc 115hp water leak

I have a 115hp Merc outboard that developed a water leak around the top spark plug. I noticed it while I was out fishing. It did not affect the power, so I assume it is just a gasket? How hard is it to pull off the head and repair this? Does any know where I can go to see a exploded view of this area?

Re: Merc 115hp water leak

It's not a cylinder head so to speak but a water jacket cover.

It's common for them to leak, and no guarantee changing the gasket will stop the leak. The bolts around the edge of the cover have captured nuts at the blocks edge, but any bolts into the block itself might be tough. I think you might be able to drop the lower cowl enough to get at the bolts provided none of them break or need extra attention. If that happens be prepared to pull the powerhead.

I've found in the past that if I scrape, degrease, and blow out around the base of the plug before removing, then replace plug with a nice clean fresh one with about an 1/8" +- bead of silicone around the gasket washer area and let dry it makes for a satisfactory semi permanent repair. There is only about 5psi in there.

Some people just let em leak.

Re: Merc 115hp water leak

I had the same problem. New gasket did not help.
No gasket and rtv blue has held up for a year now with no problems. Make sure you scrape all of the corrosion off the mating surfaces.
And for sure you want to fix it or the water will drip down and cool off your plugs and cause them to foul and even stall out your motor at idle.