no_leaks_small.jpg (16556 bytes) Ingress via boot Firewall

Water leaks through the boot/engine bulkhead is typically related to the position that the car has been parked in. If you park with the front of the car facing up hill, the water drains readily out and over the rear lamp units. However, if you park on an incline with the nose of the car pointing downhill, water tends to pool around the boot gasket in the gutter around the boot lid aperture.

To confirm this, remove the boot carpet, and take out your trusty hose-pipe. Then test the following problem areas:

  1. Around the rear light lenses to exclude a leak around the lights.
  2. Around the 'MG' badge and the high level brake light
  3. Apply enough water to the boot lid shut face area to ensure that the drainage 'gutters' or channels around the boot aperture are properly flooded.

Remember to leave the car standing for a period of up to an hour while inspecting for water ingress - if water is entering via the bulkhead for example, the water path is tortuous, and therefore it can take quite some while for sufficient water to collect in the boot to become obvious.

Undoubtedly, this process is made easier by removing the boot carpet - it makes the water ingress easier to spot!
Why does water enter via the boot-shut rain channels?

When the car is facing downhill on a slight incline, the water channel on both sides of the boot and engine bay is effectively tilted beyond the horizontal. This means that instead of water flowing rearward, down and over the light clusters, it flows forward and collects in the forward corners of the boot/engine bay rain channel and there builds up into a puddle (as can be visible in the figure opposite).

Because there is no drain hole in the forward corners of the rain channel, the puddle enlarges until it reaches the level of the gap between the engine bay seal and the boot seal (see figure, right).

From this point, the water can then flow down into the engine bay along rear bulkhead/firewall on either side of the car. Because there are a number of holes in this bulkhead ranging from 5mm to 20mm in diameter, the water is able to tracks into these, and into the space between the rear engine bulkhead and boot bulkhead. From there, the water will exit down and out into the boot floor, and accumulate in the base of the boot floor, in the central rectangular depression.

pooling_around_boot.JPG (30057 bytes)

This particular leak can be solved by:

a) not parking nose down on a slope - or at least not for prolonged periods in heavy rain. This worked well for me - I have changed the way that I part the F on my sloped drive - no more damp boot!
Or ...
b) Seal the two 20mm holes in engine/boot bulkhead cross-member/ bulkhead with suitable 20mm rubber grommets on the engine-side of the bulkhead. The holes may be obscured from view on cars built from 1997 due to the insertion of insulating material, so will need to be displaced to identify the holes.