40 HP Merc leaking water from spark plugs?

[r16409]

Hi,<br /><br />Just bought boat and 40 HP Merc, (not sure of the exact year). I ran it in a trash can for a while and it was running very good. Took to the lake today for a test run. Again it was running very good and not running hot at all. I several times removed the cover and felt the motor and it was not hot. After a few runs I noticed water "pooling" in the engine compartment below the spark plugs. Closer inspection reveled that water was comming right from the spark plug,(the base of it where the threads start). I brought the boat home and again ran in the trash can and now noticed water comming from both spark plugs. Otherwise the only other thing that seemed odd. Was the pressure that water was comming out of the "pee" hole when the motor wat running. It was gushing out of there. I think water is getting into the cly's but not sure why or how it can be comming out of the spark plug holes. <br /><br />Another thing that also started after I noticed the water commig from the spark plugs is the motor started missing.<br /><br />I was hoping to get this thing out to do some fishing so I hope this not a major set back. The fact that there is a miss leads me to believe that water is getting into the combustion chamber. I was hoping that it may be at the head or a gasket.<br /><br /><br />Any ideas greatly appreciated.<br /><br />Thanks,<br />rick

 

[AMD Rules]

Re: 40 HP Merc leaking water from spark plugs?

Sounds like the water jacket gasket is leaking -around- the plugs. That cover plate gasket is known to leak. Might be easy to try and seal it from the outside, but then again the gasket is replaceable.<br /><br />Check out this similar link<br /><br />To check for water in the combustion chamber, remove spark plugs and inspect them. Water should appear as small droplets/beads. Shine a light in the cylinders....does it look steam cleaned?<br /><br />Your miss may be attributed to carb issues, if you're lucky.<br /><br />Good luck.

 

[r16409]

Re: 40 HP Merc leaking water from spark plugs?

Thanks for the reply.<br /><br />This motor is a 1979. I did pull the plugs and examined the comubstion chamer with a light. The clynders do not seem to be steamed cleaned... The miss is worriesome because it started "AFTER" water started leaking from the spark plugs...<br /><br />How do I "seal" water jacket gasket without removing and replacing the gasket???<br /><br />Thanks,<br />Rick

 

[r16409]

Re: 40 HP Merc leaking water from spark plugs?

After further inspection I noticed that all the bolts holding the head cover on were very corroded and one had a crack in the casting along side the bolt head. I think that this may be an issue with the head cover gasket or the head may be cracked. Assuming that is what it is and I can manage to remove it does anyone know if this head cover would be worth replacing or if I can find a used one anywhere?<br /><br />Thanks,<br />Rick

 

[r16409]

Re: 40 HP Merc leaking water from spark plugs?

I removed the power head and was able to remove 5 of the 10 bolts. I drilled out the others. Picked up a new water jacket gasket. The tech at the local merc shop said NOT to use any sealant. He said to make some "shims" to go around the area that circles the spark plug hole. I read all the similar posts but it is unclear weather or not I should use any type of sealent or weather to use the shims?<br /><br />Also, the cover does not set flat it titer totters a bit. Should I try to see if it will bold down straight or try to find a used one?<br /><br />Thanks