water from spark plug

[2slow2go]

Following up with my other thread(mercury 402 - problem) , I'm currently at the cottage, and I ran the boat/motor in the lake with the cowling off, there was some bogging but did run great after rotating the plugs. I noticed that the upper spark plug around the threaded part there is water coming out while the motor is running not alot of water but at WOT there is about a drip every 5 seconds?
Whats the deal? get rid of it or is this a cheap fix?

Thanks in advance guys.

[matt h]

head gasket or upper water jacket!! (if there is one on that motor)

[Nos4r2]

It's a blind bore I think. It'll be upper water jacket.The accepted bodge on a 402 is to clean it up and araldite the leak up as the cover is unlikely to come off without shearing every single bolt and the helicoils will cost nearly as much as the engine is worth.

[2slow2go]

Originally Posted by Nos4r2

It's a blind bore I think. It'll be upper water jacket.The accepted bodge on a 402 is to clean it up and araldite the leak up as the cover is unlikely to come off without shearing every single bolt and the helicoils will cost nearly as much as the engine is worth.

Can you give me more information on araldite? What part of the motor do I apply this to? (is this stuff like gasket in a tube stuff)?
The motor is a 1978, 402HP.
I did open the square box on the left side from the back (spark plug) that the water line goes into because it was all bugged up with bugs and mud, but I just put that cover back on and never thought anything of it (the gasket). Could this be my bogging problem all along? Now that I think about it, thats when all the problems started.

[Nos4r2]

Originally Posted by 2slow2go

Can you give me more information on araldite? What part of the motor do I apply this to? (is this stuff like gasket in a tube stuff)?
The motor is a 1978, 402HP.
I did open the square box on the left side from the back (spark plug) that the water line goes into because it was all bugged up with bugs and mud, but I just put that cover back on and never thought anything of it (the gasket). Could this be my bogging problem all along? Now that I think about it, thats when all the problems started.

Pics would help at this point as I'm not sure which square box you mean.

Araldite is an epoxy adhesive. JB weld would do just as well. However, given what you've just said, some more clarity is required before you go doing anything like that.

[2slow2go]

Originally Posted by Nos4r2

Pics would help at this point as I'm not sure which square box you mean.

Araldite is an epoxy adhesive. JB weld would do just as well. However, given what you've just said, some more clarity is required before you go doing anything like that.

Sorry about the delay, I had to wait to get back home to upload photo's.

Below is a couple of pictures;

The square box I was referring to is the one with the 2 houses going in, just below the "ROCKET". So this is the one I removed and it was full of mud and bugs.


Here is the other pictures;

[Nos4r2]

That looks like your fuel pump. What was the mud/bugs like? Wet and full of fuel?

[2slow2go]

Originally Posted by Nos4r2

That looks like your fuel pump. What was the mud/bugs like? Wet and full of fuel?

I know forsure that the black hose is fuel and the white hose is water for the cooling system.
The mud and bugs (worms actually) where kinda wet and gooey and was stopping the flow of water thru the motor.

[Nos4r2]

Ok, without the engine in front of me I'm stumped now. I can't see any reason why an engine would have both fuel and water hoses going into the same place.
I reckon you need to get over to Iboats forumsand ask about this on their merc problems area. It's 5 years since I worked on a 402 and I'm remembering why I don't like them now!


It seems to be one of the few mercs I don't have a manual for as well.

[2slow2go]

Originally Posted by Nos4r2

Ok, without the engine in front of me I'm stumped now. I can't see any reason why an engine would have both fuel and water hoses going into the same place.
I reckon you need to get over to Iboats forumsand ask about this on their merc problems area. It's 5 years since I worked on a 402 and I'm remembering why I don't like them now!


It seems to be one of the few mercs I don't have a manual for as well.

LOL... Thanks for your help. I will hit the iboats forums.
Thanks again,