I sealed the right tank back in October, but hadn't yet leak checked it. The weather was quite a bit warmer (mid 50's :o) ) today that it's been lately, so I took the tank outside to get that job done. I pumped the tank up to 1 psi, using my vinyl manometer tube as a refernce. I then brushed a soap solution over all joints and rivets. Unlike the left tank I did find one leak. Its along the top line of skin to baffle rivets, roughly in the center of the tank. Photo 2 is the same area of the tank just before before I installed the baffle. The offending rivet is circled. There is a discontinuity in the sealant a couple of rivets to the right that I didn't notice at the time, and I think this might be the source of the leak.
Since only the rivet head and not the joint itself is leaking, I'm not going to jump straight to cutting an access hole in the baffle. As a first try, I'm just going to remove and reinstall the rivet, making sure it gets installed wet, including the underside of the head.
Leaking sking to baffle rivet on right tank.
The offending rivet hole prior to assembling the baffle to the tank.