After a lot of searching on the net about this problem, which is a common one for the early Freelanders, a few causes and fixes turned up for this problem.
- Loose nut cage
The rear subframe is attached to the chassis with four long bolts, these bolts are inserted from underneath the car and go through the subframe arms, then through a thick chassis rail. Inside the chassis rail is a square nut that holds the bolt in place. This square nut is encased inside a metal cage which is welded directly to the chassis.
To access this nut and cage you can pop out a plastic cover in the boot floor, there are at least four of these. But the problem one of the four is always to one on the right side of the car, and the most forward one of the two right one's.
Now comes the important part! Most people suggest that this cage can be loose, and is the cause of the problem, I assumed this was my problem, but was wrong! I lifted the car and removed the bolt, when the bolt was almost out I could move and wiggle it around with the nut still on the threads on the other end. Because of this I assumed that my problem was indeed that the cage had broken loose and I simply needed to weld it back in place.
I decided to remove the carpet out of the boot fully, and cut open the floor in an X pattern around the hole. Now I could see the nut but started to doubt that this was the problem. It looked in good condition, and the cage itself was welded firmly to the chassis. I could move the nut a little inside the cage but started to think this is normal. To check this I removed the other three bolts one by one from below the car, and all where the same. Once loosened (not fully removed) I could move the nut around a little inside the cage (not fully rotate it though).
Now I had a hole in the floor, and no solution to the problem.
- Puddle welding tubular cross member
I found this solution in an official Land Rover Technical bulletin (0112). I could hardly image this was the problem, and the welding would be the solution to this problem. In the same bulletin Land Rover basically says the same and comes up with the second suggestion to replace the entire right hand longitudinal rail of the chassis. This is a major repair involving expensive parts and lots of work. I skipped this.
- Welding and Fixing the Actual Crack
On a number of forums I found that more people had had the same problem and fixed it themselves. It actually is a pretty simple fix as long as you can weld (or can find someone that can and know what he is doing).
The repair consists of removing the subframe and cleaning the surface of the chassis where the subframe meets. I welded the crack to make sure that all is back to normal on the chassis rail. I welded on a metal plate as wide as the chassis rail, and about 15cm long. The plate should have both the holes for the center pin and the bolt. The plate was welded all around, and around the hole where the bolt goes through.
To be sure we did the exact same at the left hand side of the car. To keep it a bit balanced, although this may not be necessary. We left the rear subframe mounting points as they were.
Both metal plates where coated with Tectyl and we reattached the subframe. After this repair the clicking noise had gone!