Great write-up and pics, Randy.
Just to consolidate some of the measures from gas-tank topics elsewhere
, here are things an owner can do to preserve existing tanks.
1. Prevent water egress* [ *A path or opening for going out; an exit.
] above the tanks.
This means, repair any peeling or crinkling on the black edges of the quarter windows (harder to see on G-bodies). Once removed and re-primered, put an extra bead of sensor safe RTV around the window on the back-side. Lotus used a thin bead, there is plenty of room for more and it will not show.
Also, RTV around the junctions of the air ducting on both sides. These are riveted on the inside. They are not especially water-tight.
2. Prevent water egress through the wheel wells
There are two through-bolts on the forward side of both wheel housings. The bolts support the upper tank-boards. Clean any undercoating from the bolt-heads, seal with RTV on the wheel side, then re-undercoat the wheel wells.
3. Prevent water egress into the underside area of the tanks.
Four-cylinder owners can install rubber seals on the engine bay undertray (or, on the bodywork around the large tank access holes). I used a bulb seal 1/8" high from the Home Depot.
I pulled my OE tanks for inspection during my engine refresh, and found that these measures had prevented most of the corrosion. In fact, my OE tanks were still sound, so I just had to POR-15 the surface rust on the outside and reinstall them.
My car had been driven for long periods through many wet conditions (Hurricane George in '98 and Hurricane Katrina in '05). In both those years, we drove in downpours for 6 - 8 hours straight...
I also used silicone hose beading to protect the upper and lower flanges instead of any foam on the underside when I put my tanks back in.
Further, be careful
when washing your Esprit. Don't use a high-pressure spray around the rear quarter windows or air vents (both near the windows and in the lower sill).
One final thing I do is run a dehumidifier in my Lotus's garage. This is especially important where daily drivers share the space.