Us1 or Jay Smith

[Capt.Insane-o]

What the hell causes this? It's from helmut's post in general, My 260 does it every 10 hours on the dot, and I've had a couple 2.4 's that have split the fire ring too. :confused:

[stvhelm]

does it happen in the same spot on yours or is it different every time? that happened to mine in 7 different locations between the 2 headgaskets within the 10 breakin hrs I have on the motor.

[Capt.Insane-o]

:(

[us1]

I have never had that happen. Check the deck and the head for flatness. How much compression are on these motors

[CDave]

Things I've seen cause that on 4 strokes, uneven clamping, overtorquing, detonation, too far advanced timming, too high compression/cylinder pressure.

I would think the same things would cause it in 2 strokes too.:confused:

Wish I could help you more. I'm sure US1 and Jay can.

Edit: looks like I hit the post button a few sec. after US1

[Jay Smith]

I haven't seen a fire ring split like that before , mostly when I witness a head gasket failure it burns out at a single point of weakness ! That seems like a faulty gasket. Might try "step" torquing( start off at 20 ft lbs and torque in an X and make the X larger and larger till sequence is complete then go to top torque number , I use 38 Ft lbs and has worked GREAT for us over the years) If the failure was on one bore I would tell you to look at the deck flatness but as you saythe problem moves around so that kills that theroy !

My opinion,

[Capt.Insane-o]

On my 260. It's a 92. I will pull mine thursday night again and see what they look like. They have been it there for 8 hours now. I also have a couple sets of merc gaskets I will try. i have used aftermarket gaskets up 'till now and will be going back to merc.

[Capt.Insane-o]

i hate it when the experts say they have never seen this before.:eek:

[us1]

That was my next question, are these Mercury gaskets. That might explain a lot.

[mercrazy]

i've seen it. it was on a cheap gasket. the metal is too thin and brittle.