[rifleman_maynard]

I started the outboard for the first time this AM. I had it on the muffs, running 50:1 premix and sea foam(until I can go through the oiling sysem) with the sub (inboard) oil tank disconnected as it has a epoxy/glass patch setting up right now.

I had sprayed the sparkplug holes with sea foam a couple of weeks ago, so when it started after about 10 seconds of cranking it smoked quite a bit. As it warmed up and ran for a few minutes this improved.

The engine ran a bit rough as I expected it might given the Yamaha shop's report of a low compression cylinder. After a minute or so though it smoothed out a lot. I looked it over carefully while it was running for leaks/smoke/whatnot. There were a few droplets of water appearing at the line of the head gasket on the right side between the upper and lower cylinders. When the heads felt warm to the touch, I killed it, removed the plugs and checked the compression.

Starting at the bottom portside cylinder going clockwise: 102, 102, 98, 60psi. The spark plug in the low cylinder was interesting. All the plugs were dark not black and a bit wet with oil or fuel. The plug from the low cylinder was a little lighter over all but on the side toward the area where the water leak was, the insulator was much lighter from about 2 o'clock to about 5 o'clock.

So, I have a leaky head gasket. I need to pull the head, inspect for corrosion and flatness, replace the gasket (with OMC sealer per rodbolt's post on the subject?) and retorque everything to spec.

Is there anything else I need to look at while I am in there? Cylinder walls and piston tops of course.

Thanks for any help!

[rodbolt]

you about covered it.

[rifleman_maynard]

Perhaps the one thing I am really good at is gleaning the collective wisdom of an on line community like this forum. I make a pretty good living solving problems that I would not have a clue about without the communites on the net.

That whole list was sifted out of posts from folks like rodbolt, Ray Neudecker, and all the other experts on this forum.

Just in case no one has said this recently (or at all) y'all are public benefactors and menschen one and all.

[rodbolt]

I think mostly my artheritis leaves me with to much time at the keyboard.
that and my honey lives in Caracas VE and we chat a lot and she types slower than I do .
however glad I could help in some way.
if ya find a blown head gasket then you HAVE to go find why it blew or it will pop another.

[rifleman_maynard]

Well, when I removed the head, the low compression cylinder (bottom right) revealed multiple scores around its circumfrence. The edges of the piston look as if they are slightly damaged. The head is not battered. The other cylinder looks pretty good, though it does have a ridge at the top and a couple of small discolored spots. I think I will try to get some useable pictures.

So, do I proceed with the tear down or is there something else to do first?

I have, I think, the Sealoc manual on CD, purchased on ebay (is that thing pirated?). It is pretty well written but a bit general. I also have the Yamaha parts manual. Should I get the Yamaha service manual before I begin? The Yamaha parts web sight lists the 115 ETLK service manual as out of stock.

I have all winter to get this done, I am sure I will need information, advice and reassurance. I know I can get it here.

[rifleman_maynard]

Let's see if these are clear enough to show anything.




Is that layer of carbon a possible source of the problem? ie, crudded up rings breaking?

I think I will spend the rest of the afternoon clearing out and clenaing up a working space on the bench in my garage.