The first time I realized my XJ40 had a leaky boot was when it was still in Japan, and photos of the car had been sent to me. My agent in Japan said he'd noticed the musty smell of a wet boot, so I set to work thinking what to do about it when the car finally arrived here in Dominica. The first thing I thought about was the boot lid rubber, generally a frequent cause of boot leaks. I eventually found out that XJ40s almost always suffer from WBS (Wet Boot Syndrome, or is it the owners who suffer from that).

The points I was told to check by helpful members of these forums were the petrol filler area, antenna grommet, and somewhere along the lower panel above the bumper. The first thing I did was to seal up the area where the body panel meets the housing around the filler cap; that didn't work, because pouring water there still revealed a leak into the boot. I decided that I hadn't applied the black silicone sealant properly, and ripped it off, and re-applied it, this time extending the silicone to actually cover the area almost to the top of the aperture, so water couldn't seep into the section where the body meets the housing underneath, and after one or two touchings up, that appeared to be successful. The following morning, there was water in the boot again - I poured more water over the filler area, and no, the leak was gone - at least from the filler area.
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Next, I noticed the rubber grommet at the base of the antenna did not appear to be sitting flush on the body, and upon closer examination, discovered without a doubt that water was also entering through the grommet; and of course I noticed the tell tale signs underneath. I removed the old grommet, applied a base of clear silicone (to keep everything in place and to save the black silicone for exterior use), and when that was dry, applied the black silicone over the clear, and shaped it with the help of tape to resemble (I hope) the grommet it replaced. With that dry and more water to test it - no leak, so that was an end to the leaky boot...or so I thought, for next morning, there was the regular supply of water smirking at me from its usual place in the forward section of the boot floor.

More water tests definitely indicated that the sections near the filler and the antenna that I repaired were not leaking, and neither was the backlight glass nor the boot lid rubber. I soon noticed a few drops of water near the base of the right tail light, and discovered that the inside was wet, so I assumed that the lower compartment of the light would eventually fill up with water and overflow right into the boot. I removed the whole assembly and filled it with water, and turned it upside down, and sure enough, water was leaking from the top section, where the lens is attached to the main body of the unit. More clear silicone in that area, (to lazy to bother to test outside car) reinstalled in the car, and tested when dry - no water leak apparent. I was thinking of applying a seal to where the unit actually met the body, but I thought I'd do that if i discovered more water ingress, which I did not. It appeared that my boot had been leaking in three areas at the same time, and hopefully the job was now in fact completed.

It was; we've had some rather heavy rain, and my boot's still dry, so I'll have to find somewhere else to store water when the household supply gets shut off.

I can't find the cable that connects my camcorder to the computer, so pictures will have to wait.

 

Sounds like you have pretty much got things covered there.

The only other area that I can think of if you have future problems is the drain pipe from the bottom of the fuel filler rubber.

If it comes off, or splits then your boot will fill with water pronto.

To access it you need to remove the left side panel and rear panel behind the spare inside the boot.

A 10 minute job but worth a double check especially if you ever do any work on the fuel tank.

Mine, did detach, and the boot filled to around 4 inches overnight

 

Sure we can wait for the pics to arrive but good thing is you fixed the problem which is good

 

That was the first thing I checked, and it got re-checked when I poured water down the filler to check the seal...so that seems okay for now. The nice thing about it is the gurgling sound you hear as the water flows through it; but thanks for that information on how to get to it.

I've also noticed two other drain hoses in the boot - one from the antenna, and the other from the battery. I must say that I've never encountered a battery with a drain hose!

 

Harks back to the days when batteries required topping up, you wouldn't want the spilled acid rotting out your boot floor.

Mark you, I don't have this feature on my RHD XJ40, the battery is in the engine compartment. Much better IMHO.