When we ran our 2014 Beta 60 flat out, for the first time in a few years, in the tropics it got hot (not enough to alarm)
When we opened up the heatex, we found some junk plugging the first pass, and (surprisingly) even more at the entry to the second pass. Refer to attached photos
Any idea what it is? We have a strainer on the cooling water intake
Also, the heatex feed pipe had lots of scale. Any idea why?
When laying up the boat (usually for 6 months) we run fresh water through the sea-water system
The first three pictures look like sea junk that got past your sea water intake strainer. The fourth looks like classic scale, which can be dissolved with lots of time in vinegar or a shorter time (careful) in diluted hydrochloric acid (sold for swimming pools as muriatic acid).