Water in cylinder... please still read!!

skholley

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Mar 26, 2012
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I know you guys love these "after winterization cracked block questions" but here I go! 1989 mercruiser 5.7 350 magnum with through hull exaust. took boat out of storage, went to change plugs and had winterization antifreeze in my #7 cylinder. Changed oil and there was not a drop of water in it. Cleaned all plugs (none of which had any water) and fired it up. It ran great. after about 15 minutes I shut it off and pulled the plugs. No water in any of them. Let it sit and checked again, still nothing. Three days later did the same routine and nothing again. Have dog house and all seats out of boat now and don't know what to do? Thankful for any help you can give....
 

RogersJetboat454

Commander
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Jul 9, 2010
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2,964
Re: Water in cylinder... please still read!!

Welcome to Iboats SK.

Out of curiosity, do you boat in salt? And if so, how recently have you inspected/replaced your manifolds and risers?
 

skholley

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Mar 26, 2012
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Re: Water in cylinder... please still read!!

It has never been in salt. and i have owned it for three years and never have replaced the risers or manifolds.
 

Don S

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Aug 31, 2004
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62,321
Re: Water in cylinder... please still read!!

Since it's only in one cylinder, pull the riser on that side and check the gasket surface between the riser and manifold. It may be only a faulty gasket. Were they OEM or paper aftermarket gaskets?

View attachment 01-13 Water Intrusion.pdf
 

skholley

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Mar 26, 2012
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Re: Water in cylinder... please still read!!

I will pull the risers and replace the gaskets with OEM gaskets. Will it be a standard gasket even though I have through hull exhaust... so I can order a new one... I will let you know what kind of gaskets they were... and the outcome. thanks I appreciate the help.
 

skholley

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Mar 26, 2012
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Re: Water in cylinder... please still read!!

Hey Don. I just realized i could click on the picture in your last post and it was an attachment!! That manual really helped. I fall into a few different catagories on there. I was on the trailer when I turned it off last to winterize (Maybe even tilted forward!), I also let it idle for a while before I shut it off. And it seems like alot of water ingestion problems stem from through hull exhaust! I am still going to pull the riser and replace gasket... but I am thinking about trying the the Mercury Parts Exhaust Resonator Kit. Do you have any type of review on this kit? thanks again!! My stomach is starting to settle!!
 

Don S

Honorary Moderator Emeritus
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Aug 31, 2004
Messages
62,321
Re: Water in cylinder... please still read!!

It's not some kit you buy, it's just the manifold to riser gasket. Which one depends on your cooling system.
Here is another service bulletin on the gaskets.

View attachment 99_10 Exhaust Gaskets.pdf
 

skholley

Recruit
Joined
Mar 26, 2012
Messages
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Re: Water in cylinder... please still read!!

It sounded to me liek something different than gaskets! 6. Boat exhaust systems (engines with thru-hull exhaust only).
a. Engines with thru-hull exhaust systems can have a ‘tuning’ effect. Exhaust hose
length, 45, or 90 fittings, location of collector and/or muffler and the thru-hull exhaust
tip all can affect water ingestion. The only way to test for this condition is to
monitor the amount of water that collects in the runners of the exhaust manifold after
idling for 45 minutes. Engine has to be at normal operating temperature before starting
the idle test. Using Exhaust Resonator Kits in the exhaust hoses will help stop
the ‘tuning’ affect in the exhaust system. The Mercury Parts Exhaust Resonator Kit
does not cause any horsepower loss
 
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