Volvo D4-260 heat exchanger - plastic tube

[jswhal]

I'm planning to flush the heat exchanger, and noticed that on the aft end cover there is a zinc, and a fitting with a foot long plastic tube that hangs below the engine. Any idea what this tube is for?

https://photos.app.goo.gl/zpkQHTRNAqhdYgS97

 

[Newf]

Just guessing, but could it just be a drain line to drain water out of the exchange when not in use. I have one on my exhaust elbow that I use after every trip to drain off the salt water from exchanger and elbow. I started doing this after I had corrosion issues on the end of the exchange casting. If the boat is going to sit on the trailer for more than a few days I also do a fresh water flush on the system.

What product are you using to do your flush?