Re: Water coming out of Spark Plugs on 1986 Mariner while running
I dunno if I'd want to even mess with the cover. Take a look at the first set of pics, you'll see that one of the cover bolts already has the head sheared off. And look at the salt deposits around that bolt. You can imagine what's around every other bolt holding that cover to the block!
I'd wager that almost every bolt will break trying to take it apart, even if heat is used.
On this type of block, the cylinders and block are cast as one integral unit. The flat pad you see where the spark plug screws into is part of the cylinder and is machined flat, along with the block.
The pad is round in shape and the last set of pics shows the edge of the pad which has eroded back to almost the spark plug hole.
Normally the water jacket cover & gasket form a nice seal against the 4 flat pads. In this case, yours are getting eaten up by corrosion, the metal just gets all nasty/flakey and goes away. Seen quite a few Salty Dogs do this.
Just removing the cover and installing a new gasket sure ain't gonna make this bugger seal up!
If you were able to get the cover off, you'd proably have to try and build-up the rotten area with weld, but that's pretty dicey since there's not much left to work with. Might possibly be able to use some RTV (Hi-Temp Red or Ultra Grey) on the inside, coupled with a skin of RTV on the outer side once it was bolted back up. That "plug" of RTV will probably hold pressure since it's usually no more than 10-12 psi.
But what I'd try doing first, before removing the cover, is clean the eroded area the best you can. A good spray of carb cleaner should degrease pretty well.
Then, run a bead of RTV in there. Try to push some RTV in the eroded area with your finger, once it hardens it'll help plug the hole.
Red Hi-Temp RTV works pretty well, but there's a newer-type that's pretty hi-strength, the Ultra Grey. So maybe try some of that.
You don't really have much to lose except the cost of a tube of RTV and if it does work, it's a far less intrusive repair than removing the cover.
Those bolts look like they're in there so bad that you'd probably have to pull the powerhead to gain enough access to the bottom bolts. Usually you wouldn't have to, if they'd come out easily. But I can guarantee ya, these ain't those! They'll fight you all the way. Then it's the joy of drilling and tapping a bunch of busted bolts!!!!
BTW the other hole is factory-drilled and if I recall, can be used for an optional temperature gage. No need to worry about it, as it's supposed to be there.
HTH & G'luck..........ed
!!!!!!!!!!!!!!!!!