1987 inline 6, 90 hp Mercury, water by spark plug

RandyJ

RandyJ

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I was having trouble with this motor running rough. I think I've got it running okay now but there is water coming out of the head around the top spark plug... I looked and there appears to be a small threaded hole next to the spark plug... am I correct that all I need to do is put a bolt/screw in there to plug the hole and everything will be okay? Can anyone tell me what that hole is for? I assume this head is like on other merc's just a cover for the water jacket.
 
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Laddies

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Re: 1987 inline 6, 90 hp Mercury, water by spark plug

I doubt that the water is coming out of the hole every one I have seen the gasket is blown right where the indentation next to the hole for the temp sender goes, if it's a fresh water engine it should not be much of a job to change the gasket, just use care on the bolt not to break them off. If it's a salty then your better off trying to seal if with silicone or epoxy.
 
RandyJ

RandyJ

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Re: 1987 inline 6, 90 hp Mercury, water by spark plug

Laddies said:
I doubt that the water is coming out of the hole every one I have seen the gasket is blown right where the indentation next to the holr fot the temp sender goes, if it's a fresh water engine it should not be much of a job to change the gasket, just use care on the bolt not to break them off. If it's a salty then your better off trying to seal if with silicone or epoxy.
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I don't have a clue what a HOLR FOT is... but the water looked like it was coming from around the spark plug until I investigated and it is coming from a threaded hole right next to the plug. What appears to be a head is actually just a cover for the water jacket.
 
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Laddies

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Re: 1987 inline 6, 90 hp Mercury, water by spark plug

Sorry for the misspelled words, I will be more careful in the future. Maybe your English teacher may help. Good Luck.
 
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arsenalpsu

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Re: 1987 inline 6, 90 hp Mercury, water by spark plug

I had the same issue, that hole is for the temperature sensor and will not allow water out. It's coming from around the water jacket around the plug. I put some silicone around the hole and it seems to be holding. If not you'll have to pull the cover and replace the seal.
 
RandyJ

RandyJ

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Re: 1987 inline 6, 90 hp Mercury, water by spark plug

hmmm.... looks to me like a job for jb weld. this one doesn't have a temp sender. I'll give it a shot and if it still has problems I'll take a more serious approach. It's on an old pontoon that I use for a work barge.
 
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