1990 yamaha v4 115ceto 2 stroke - water in cylinder

[midgiegualla]

Was returning home from a fishing trip last week when motor just stopped.Was running well all day so was a bit surprised . Thought maybe a fuel problem.
The engine would start but run very rough at idle.When put into gear would immediately stall.
Radioed VMR for a tow. (First time I have had to be towed back in 27 years.) Very Embarrassing !!
While running motor when i got home i noticed one cylinder was missing (Port top). Removed spark plug and noticed water in cylinder.
Removed Cylinder Heads to find out what could be wrong.
The Head Cover , Cylinder Heads were in a lot better condition than i expected after 27 years of salt water use.
But the problem was a pea sized hole in the port side head . This was the only major corrosion in the port head.
I then removed the Starboard side head. To my amazement there was a hole in the starboard side very similar to port side hole but just a “mirror image”.
This surely can’t be a coincidence I wouldn’t think. I have uploaded some photos.
The only explanation i can come up with is that both holes are right next to where the Temp Sensors were situated in head.Maybe some sort of electrolyse ???
Any Thoughts ?

[ausnoelm]

Clean out the water, use some sort of protector spray on the cylinder walls, make sure crankcase is dry, buy new or second hand heads, refit, go boating for another 27 years.

[midgiegualla]

Yeah ausnoelm , Have cleaned it all out and have ordered all new parts. Even if it lasts me another 15 years it will see me out. By then i will be too old to pull a fish in !!!!

[TownsendsFJR1300]

I suspect with the engine heat, (especially right there), salt got cooked to the area when you turn the engine off and water drains from a hot block- Thus more corrosion in that area.

I was given a Mercury (maybe a 115HP) many years ago (decades actually), exact same issue, same location..

On that particular engine, the head was part of the block (couldn't be removed- 2 stroke). Cleaned it up real good, trimmed up a small piece of aluminum and had it welded in.

Couldn't get inside the cylinder W/O splitting the block(complete engine tear down) but the engine wasn't run much after the issue started... (lucked out)....

Worked great! Had to buy a another hull to bolt it to and then sell it!

[midgiegualla]

Yeah , Looks like it's just what happens after years of work in a salt environment.
I have ordered all the parts including new Heads,Head Covers,Thermo Covers etc, etc .
Just need some advice, Do I need to put any chemical additive on the head gaskets when fitting ?
I was NOT going to use anything.
To me it's like going out in the sun with TWO hats on !!
Any advice appreciated.

[TownsendsFJR1300]

The head gasket does NOT require any sealant.

Nor does any other covers / gaskets for your particular project..

[99yam40]

the Service manual will show if any sealant is needed on anything, hope you have one for your motor

[panasonic]

Yeah , Looks like it's just what happens after years of work in a salt environment.
I have ordered all the parts including new Heads,Head Covers,Thermo Covers etc, etc .
Just need some advice, Do I need to put any chemical additive on the head gaskets when fitting ?
I was NOT going to use anything.
To me it's like going out in the sun with TWO hats on !!
Any advice appreciated.

What does the top of the block look like, where the cylinder heads mate up?

[midgiegualla]

the Service manual will show if any sealant is needed on anything, hope you have one for your motor

Yeah have a CLYMER YAMAHA OUTBOARD SHOP MANUAL (very handy)
Had a quick read and can confirm what TownsendsFJR1300 said , " The head gasket does NOT require any sealant "

[midgiegualla]

What does the top of the block look like, where the cylinder heads mate up?

It looks in pretty good nic .