We have just gotten around to removing the end caps on our engine heat exchangers. The first time since launching. As you can see, this was somewhat overdue!

The debris is mainly bits of sacrificial zinc anodes. The starboard engine was much cleaner.

We used a piece of 4mm (3/16″) welding rod to check the heat exchanger tubes for debris (they were clean).

The Deere manual recommends a heat exchanger check every 1200 hours. We will henceforth adhere to this regimen.