Hairline cracking on inside clutch cover

[roadiemort]

They are formed by continuous heat cycles in the castings interior plating, looks bad but really isn't.

[MikeyC]

I've seen it on the inside of mine as well, I think it's from the casting method and cooling of the aluminum.

[brianmac]

Yeah Yamaha is a metallurgy company or was first and foremost and then it morphed into way more than that. After Y2K they dove into four stroke outboard motors, in the first couple of years were plagued by exhaust housings corroding and cracking clear through, that's the part that goes from the powerhead aka the motor, down to the lower unit, aka the transmission where the prop comes out. Apparently they didn't account for the corrosion that occurs there as exhaust gases pass through it, when gasoline is not accompanied by copious amounts of two-stroke oil. They they had to change a few things to get it fixed but many people with very expensive outboards out of warranty in salt water were outraged.

[Duke]

If you're not see any oil seeping out on the outside, then I wouldn't worry about it.
If it is leaking, I have a good cover that you can have. PM me if you're needing one.

[roadiemort]

Leave it the Phuck alone and move on.

[Horsehammerr]

Grind it out SLIGHTLY and JBWELD IT !!!

[Shores]

Those aren't all the way through. I've seen them on mine too. Must be just part of the manufacturing process.

[Lug Nut]

Odd place to have a stress crack???

[brianmac]

Looks like I had a little hairline cracking on the inside of my clutch cover looks weird but it doesn't seem to be creating a problem