Johnson outboard leak from spark plug hole

[ScottsdaleArizona]

I recently bought and nice old Glaspar with a 1964 Johnson 90 HP outboard… it starts right up and idles good until the water pump kicks in… At which point water starts dripping out of cylinder 4 where the spark plug is plugged in ..causing a rougher idle… I pulled the head off and noticed quite a bit of build up under the water jacket cover when I pulled off the gasket .. the other side looked clean as a whistle .. pistons didn’t look they’d seen any water at all either.. I cleaned all the surfaces extremely well.. installed a brand new head gasket and also installed a new water jacket gasket using permatex 2 non drying form a gasket sealer .. and it’s still leaking water out of the hole where the plug goes into cylinder 4.... I’m a novice at boat repairs.. but my reading leads me to believe maybe the water jacket cover is slightly warped from a previous overheat ? Also one of the 17 bolts that hold down the jacket cover is somewhat stripped.. it won’t totally bite down...eBay has a bunch of used port cylinder head assembly’s ... would A new one fix it? Any help would be much appreciated .. I’d really like to take her on her maiden voyage! I’m thinking I probably shouldn’t until this is resolved ... thx!

 

[racerone]

Install helicoil in that hole that is stripped.--- Clean threads in holes with tap.-----Run die on each screw.------Use emery paper on glass to correct imperfections on gasket surfaces.----Should now seal up with the 17 screws at 80 inch lbs.

 

[ScottsdaleArizona]

Installed a new port head and new head gasket.... still leaking from spark plug hole?? Im lost! Any suggestions are very welcome! Thx

 

[Bad Al]

Installed a new port head and new head gasket.... still leaking from spark plug hole?? Im lost! Any suggestions are very welcome! Thx

The one thing you haven't replaced is the water jacket plate!

 

[racerone]

Sound impossible that you have 2 bad cylinder heads.----Walk over to my shed and get a good one.-------I have some but no international shipping from me.

 

[ScottsdaleArizona]

The new cylinder head also had a new water jacket on it… I bought it used but doesn’t look like anything it ever leaked from it ..

 

[racerone]

Sounds impossible.-----When you find the issue you will say ----" that was simple " ----I am sure.

 

[Bad Al]

Don't use the word "new" when referring to a used part... it is misleading and confusing.

Is water gaining access to the cylinder itself?
Does water traces show up on the spark plug electrodes?

 

[ScottsdaleArizona]

Yes I’m pretty sure.. it idles perfect till water gets in there .. then idle gets rougher

 

[ScottsdaleArizona]

[No message]

 

[ScottsdaleArizona]

And it shocked me when I touched the plug wire..

 

[Bad Al]

If water is present on the electrodes of the spark plug, you'll need to find out... "From where?"

If the sealing surfaces of the crankcase (Block) or the head are worn or corroded, or the wrong head gasket is being used, that would explain it.

However,water in the cylinder, especially #4 could be due to a problem in the exhaust baffle plate area... not to be overlooked.

BUT!!..... Either case above does not explain how water is obtaining access to the actual #4 spark plug. Even if water is accessing the cylinder, it should be impossible for water to get past those spark plug threads and its related sealing washer. This leaves us to wonder if something is being left unsaid...such as.................

Possibly the water hose from the head to the thermostat housing leaking and spraying water on that spark plug!

 

[jimmbo]

Bad Gasket, warped or damaged Gasket Seal Surfaces on head or waterjacket, or cracked head/waterjacket. Not a lot of thinks to go wrong. That Fancy Bolt and Washer...

 

[oldboat1]

The housing screw hole under the plug looks to have been repaired, and the bolt replaced (appears to be a hardware store bolt, which may or may not be an issue). This area may be a source of some leaking. In combination with what appears to be a worn plug boot, that may be the source of the water incursion and the shocks -- assuming that cover is the one in use.