In article >, Father Mike > wrote:
>I have about 145,000 km on this boat. I took it in for routine work and
>Canadian Tire pulled me aside and said I had a leaking head gasket and to
>prove it they showed me flakes of brown sediment which allegedly came from
>my cooling system. The cost to repair would be around $1800.

I certainly wouldn't replace a head gasket based on that diagnosis.

The definitive check for a blown head gasket is a compression test. If it's
more-or-less normal on all cylinders, your head gasket is fine.

I share your opinion that it's probably just dirty coolant.