Small heat exchanger issue

[scgunner]

Dave,

There's no telling how long that HX has sat there unserviced but it looks like it's been a long time. If it was my boat I'd pull the HX, flush it (you'll probably find a lot of zinc debris), check the blockage in the tubes and clean them out as best as possible, but gently, then clean, reassemble and repaint. It's not that big a job and will give you an idea of what condition it's in. But be advised this HX looks very old and those exchange tubes could be paper thin or have weak spots by now which could fail at any time or be fine for hundreds of more hours, hard to tell how much life is left in it. Best option, replace it with a new 3" HX but they aren't cheap!