I was reading some posted posts on here bout leak problems and had to sign up in order to get my turn I have a 20' aluminum Crestliner which has a double hull (nearly impossible to get into and definitely impossible to put back together). It has been leaking since 2004 and I have tried everything I know to do to find and or stop the leak. I can fill it completely full of water and it will not leak a drop!!! I have gone over the few places on the hull where I thought it could possibly leak and applied 5200. I have sealed off the holes in the stern so no water could enter them and no difference...withing about 30 minutes the bilge is pumping and comes on every 20-30 minutes. The term "differential pressure" is in here somewhere I know.
Any suggestions would be appreciated. Best flounder fishing boat I have ever had.....just need this leak fixed.

Thanks guys and or gals

how about your water pressure line or the speedo line, are they leaking into the hull?

I'm running into the same thing with my G3. It was also a saltwater boat. The hulls for these boats are stamped in two halves and welded down the centerline. After replacing the only thruhull on the boat, I still had leaks. I took it to an aluminum fab guy on the lake. I needed to have some broken stringer welds redone and in the process of cutting off a section of the keel strip that covers the welded center seam, we found traces of oxidation and salt corrosion that were causing pinholes in the keel seam. Mine's not serious, but in the fall when my business slows down, it's going back to the fab shop and we are going to cut the keel strip completely off and grind/weld the keel seam.

If it's any consolation, a buddy of mine just bought a new Crestliner and it also leaks. He did the same thing as you, filled it with water and waited for the drips to start and it never did. I think the keel may be difficult to remove on the Crestliner because he said his is completely welded to the bottom on both sides. Mine is just stitch welded every 10-12 inches so it's not going to be a big deal to break it loose to grind the weld.