Did you winterize it at all last year, or did you just miss a couple of
plugs? I had a similar experience many years ago...before I knew what
had happened, the boat actually started and ran fine on my first run of
the season, but died at 50 MPH. It started again and I got back home.

A friend later discovered the cracks in the block and was amazed it
even ran. In my case a dealer had winterized the boat, but obviously
did not do it properly, so I threatened to sue them. They went
bankrupt, not because of me, and I wound up replacing the entire block
and manifolds.

What happened with your winterization?

GSS wrote:
I finally pulled my boat out of storage (way late for the summer, I
know), and discovered that I had two freeze plugs pushed out of the
block and my 1 year old exhaust manifolds had tight freeze cracks at
the back of the log. This is on a Mercruiser with a Ford 302. I
pounded the freeze plugs back into the block, and started the engine
which ran fine, but the exhaust manifolds are leaking water into the
bilge through through the cracks-not much, just steady drip. Can these
cracks be brazed shut? They are Barr Marine Cast Iron Manifolds.
Don't know if there are any cracks on the exhaust side of the manifold,
but I'll figure that out when I take them off...I know Cast Iron is
highly durable in compression and terrible in tension...the exterior
cracks are certainly tension induced from the ice expansion, so I'm
hoping the exhaust side didn't suffer any damage because it would have
been in compression.

Please respond to the group.