15 MSH missing in lower cycilinder

[TownsendsFJR1300]

Just to add to the above posts.

Between the apparent water intrusion into the lower cylinder AND the corrosion showing on the edge of your head gasket, I'd be strongly leaning towards the issue being a bad head gasket.

It would be the easiest part to fail, and looking at it alone, I'd probably replace it just for that reason. Its cheap enough and easy enough (short of busting a bolt) and there are some secrets to removing a stuck bolt if need be...

[rodbolt17]

ok
a small logic quiz.
to steam clean a plug we need water and heat, lots of heat as it must go over 212*F.

if water is in the combustion chamber how to we get heat?

see why its a unicorn?

unlike the internet myth of steam cleaning plugs, water will cause a black to brown crust to form on the plug.

as water prevents combustion there is not enough heat to flash into steam.

kinda like putting tin foil balls in the hub caps will fool a radar gun.
that one has been around a few years before the internet.

[99yam40]

ok
a small logic quiz.
to steam clean a plug we need water and heat, lots of heat as it must go over 212*F.

if water is in the combustion chamber how to we get heat?

see why its a unicorn?

unlike the internet myth of steam cleaning plugs, water will cause a black to brown crust to form on the plug.

as water prevents combustion there is not enough heat to flash into steam.

kinda like putting tin foil balls in the hub caps will fool a radar gun.
that one has been around a few years before the internet.

Thanks for posting back Rodbolt with info on the black to brown residue.

I do not remember hearing about the tinfoil balls in hub caps before, but I could have killed that brain cell that held that info

[yammie15]

Ok... thanks guys for all of this great information. But I need a **** plan.
Things seem to be centered on the head gasket or the carb. Anyone care to suggest which I should tackle first?
Bry

[robert graham]

With all that white stuff coming out from around that gasket, I'd pull the head and fix it....

[TownsendsFJR1300]

Ok... thanks guys for all of this great information. But I need a **** plan.
Things seem to be centered on the head gasket or the carb. Anyone care to suggest which I should tackle first?
Bry

You have one carb and the top cylinder is burning fine, -that eliminates the carb, move on from that.

I've never seen a plug "burn" like that. I'm trying to interpret Rodbolts posts, IF it is water intrusion.

As noted earlier, there's some major corrosion at the head gasket. IMO, I'd be pulling the head and inspect/replace the gasket and dig deeper if need be.

[99yam40]

If you do not know this yet, Rodbolt is a Yamaha master tech that works on this stuff for a living.

He posts to help others and we are grateful for his participation on the forum.
i would vote for looking for where the water is getting into the one cylinder.

Thinking more on this , I believe but am not positive, that if it was exhaust plate it would hit more than one. Could be wrong though

[TownsendsFJR1300]

Rodbolt is a Yamaha master tech that works on this stuff for a living. He posts to help others

Agreed 100%, but a quiz does NOT help the OP.

A post on EXACTLY WHAT the likely issue is / how to proceed would be VERY HELPFUL....

[rodbolt17]

typically water in a cyl is a head gasket failure.
on rare occasions it can be an ex divider plate.
on even more rare occasions its a block issue.
I would pull the head and have a look.

[yammie15]

Thanks again. I found a guy here that will lend me a torque wrench. I'm ordering parts!

I will take photos and post them here.

Again, much thanks...
Bry

[yammie15]

One last hitch... seems I need a part number for the head gasket. Can anyone help with that?
Yamaha 15MSH Year 2007
Serial Number 684K S 1057789 J

There must be a parts number book as well as a service manual. Am I right in thinking I need both?
Thanx,
Bry

[TownsendsFJR1300]

Here's the parts fisch for you head and block. If you look up and to the right, in RED, it has "Purchase Yamaha Parts". Plug in your data and your set...

2006 and Later 15MSH Yamaha Outboard CYLINDER CRANKCASE Diagram and Parts

Re the service manual, you'll need to know the torque for the head bolts, some heads are numbered on which order to torque. A shop manual would be an investment IMO.

[yammie15]

Thanks Townsends...
I don't see "Purchase Yamaha Parts" in red.
I see the parts schematic on the left, but the numbers do not match up with the parts list on the right.

Is this what I'm after:

GASKET, CYLINDER HEAD 1
63V-11181-A2-00

That's number 19 on the list but number 1 in the schematic. Very confusing.

Any ideas on this?
Bry

[TownsendsFJR1300]

Thanks Townsends...
I don't see "Purchase Yamaha Parts" in red.
I see the parts schematic on the left, but the numbers do not match up with the parts list on the right.

Is this what I'm after:

GASKET, CYLINDER HEAD 1
63V-11181-A2-00

That's number 19 on the list but number 1 in the schematic. Very confusing.

Any ideas on this?
Bry

Your correct. Part #19 is the head gasket,

The only #1, I see for that part is that there's only 1 unit needed for the engine.

The "Purchase Yamaha Parts" (in RED font) is literally on THIS PAGE, up and to the right. Its right next to "Home" in the blue horizontal bar. Right under "Yamaha genuine parts and accessories". Click on that and it'll open another page to look up parts..

[yammie15]

I found the blue horizontal bar but it was on the home page. I copied the part number into SEARCH and got the following:

This Yamaha 63V-11181-A2-00 GASKET, CYLINDER HEA is used on these models and components:

2006 and Later 15MSH CYLINDER CRANKCASE
2006 and Later 15MSH REPAIR KIT 1
2006 and Later 9.9MSH CYLINDER CRANKCASE
2006 and Later 9.9MSH REPAIR KIT 1

Is that right? Its says Crankcase....

I need to get it right the first time. If I have to reorder the gasket because I was sent the wrong one, I'll be stuck without my outboard for about three weeks. I don't have that much beer on board the sailboat

Appreciate a bit of reassurance here. Thanks...
Bry