Leaky Lund

I have a leak in my 2004 Gran Tyee Sport Lund. I read the post and answers from a couple of years ago and all of your input looked very helpful. My leaky Lund story is different, so I will try to describe it.
My leak has been gradually worse over 3 years and now makes the bilge pump run to expel 3 gallons of water every 20 minutes. On level ground, I removed the starboard live well intake screen on the back of the boat, hooked a hose to it and put the plug in the forward starboard live well and all was normal. It filled normally, overflow ran out the side port normally and when I pulled the plug, all the water ran out the drain on the bottom of the boat roughly straight down below the windshield is. No water accumulated in the bottom of the boat, nor ran out the lower most drainplug hole.

I repeated the “fill the live well” test via the left through- the- transom intake and the starboard rear live well filled normally and the overflow out the starboard overflow hole drained normally. The ice box on the port side was dry and the plug was left out. No water exited the lowest hole in the transom (drain plug hole) , but a steady drip came out of the black port just to the side and above the drain hole plug (6 ozs per minute). Pulling the plug in the starboard live well found normal drainage, but the unplugged ice box filled with 2 inches of water. No water in the bilge. Inspection of the bottom of the boat was unremarkable.
Any helpful advice or suggestions?

Potentially leaky rivets ?
Put plug in boat and garden house in the bottom of boat…look for water leaks on outside and part of the process of elimination….

Is the boat stored in cold or warm storage? Does that boat have a wash down system>

9 gallons a hour is a hefty leak. For that much water you either have a BUNCH of leaky rivets or broken plumbing. Do Deans test and than hit all the plumbing possibilities again.

did you try to plug the ports where plumbing enters the boat ? My live well pump housing had a crack in it and would result in the same sort of thing . On my lund the fitting are threaded so I screwed a cap on from the outside of the boat. By doing that I was able to pin down the issue

Dean test will identify your problem. Had a sylvan boat that got ran up to Flin flon 20 some years in a row and developed quite a few leaky rivets. First fix was installed auto bilge pump but it got annoying when it started to go off all the time. There is a place in Delano that fixes leaky rivets or you can do it yourself like I did. Got an air riveter, filled boat up with water identified the leaky ones, drilled them out and replaced with closed head Aluminum rivets. Was really not that hard of a project. Bilge pump rarely went off after that. Good luck.