1974 Mercury 65hp - water from spark plugs

[fishysmell]

I finally reassembled everything after my tune-up with some help from the forums, put on the muffs, and started her up. It was the easiest start ever and sounded good. It was spitting water better than ever, but immediately noticed water coming from the spark plugs. I shut it down, checked the water lines to make sure it wasn't coming from there, restarted, and confirmed that it was coming out of plug 1 and 3. What do I do? Where should I start?

If it helps, it's a 3 cylinder with serial 4048369. (1974 mercury 650)

 

[Laddies]

Re: 1974 Mercury 65hp - water from spark plugs

It's not from the plugs it's from the water jacket cover gasket, quite common it's usually caused from sitting around for a long period of time or from the engine overheating and is not a big job to replace, just use care not to break the bolts when removing them if you are lucky it's a older engine with nuts and bolts if thats the case they are much easier the replace as they won't need to be drilled and tapped if broken.

 

[fishysmell]

Re: 1974 Mercury 65hp - water from spark plugs

OK...thanks, Laddies. You've been a great help on this project. The hot water and detergent worked great on my distributor cap, like you recommended. This really scared me 'cause it looked like it was flowing from behind the spark plugs and I knew that had to be bad even if it didn't make sense that it would run so well. Anyways, thanks again! I'll give it a go.

edit: One last question...will it hurt anything to run it like this? After the tune up I'd like to put it in the water and give it a test and see how she runs. Is this doable or should I fix this first?

 

[Laddies]

Re: 1974 Mercury 65hp - water from spark plugs

There are a lot out there, running that have been leaking a long time and no one has noticed it yet.

 

[fishysmell]

Re: 1974 Mercury 65hp - water from spark plugs

I've been looking around for a "water jacket cover gasket" for my mercury, but can't find any references to it. Is there a more specific search term I could use to locate this gasket online?

edit: is it possibly called a cylinder block cover gasket pictured here?

 

[Yepblaze]

Re: 1974 Mercury 65hp - water from spark plugs

Scrape and degrease the area around the plug that is in there now. (Leave plug in while doing this) blow it clean.

Now remove plug and replace with new plug with a 1/8" bead of silicone around washer area. Let the silicone air cure for a couple minutes before installing as normal.

After an hour or so, or better yet next day, it should be water tight and dry till you need to remove plug.

 

[emckelvy]

Re: 1974 Mercury 65hp - water from spark plugs

Looks like the gasket to me. And yes, that is the correct name for it.

Re: the silicone fix, that's an excellent "quick & dirty" way to get back out on the water. 'Specially if you're not gonna replace the gasket right away.

In fresh water you probably won't have any issues with water dumping on the spark plugs or wires, but salt water can cause problems such as misfire. So you're much better off to not have any water spilling out of there.

At least you know you've got good water pressure, eh?!! BTW use a good grade of automotive silicone and the temp repair will hold better.........ed

 

[fishysmell]

Re: 1974 Mercury 65hp - water from spark plugs

Thanks for the suggested quick fix, Yepblaze! I like an easy alternative until I feel like replacing that gasket (and probably break the bolts and/or nuts knowing my luck). I appreciate the help (you also helped me find the serial number of my boat last year...I'd be lost without these forums).

Emckelvy, thanks for the clarification. I was pretty confused. These forums are so great, and all your help is appreciated!

Now...time to put some silicone beads on my plugs!