two known problems with the early td5's are
1. diesel seeping into the injector wiring loom - $1000ish for new loom.
An LR specialist can tell if this is happening.
2. Oil pump bolt comes loose (if no loctite) - $15000ish for new engine.
Anyone can inspect ( remove sump ) and reapply loctite.
Its actually oil from inside the rocker cover that gets into the loom, as the injector loom runs along inside the rocker cover, gaurded only by a splash shield. If its really bad, you will see little pools of oil underneath the ecu (which is behind the battery). If its this bad, it will usually result in a misfire. If its not too bad, you may still see it by unplugging the plug at the front drivers side of the motor, which is about 3-4 cm down and kind of under a bit of an overhang.
It is possible to do just the loom under the rocker cover in most cases, which will cost about $400-500 for the parts, and you can do the job yourself. The only thing is that you'd need to take it to someone with a diagnostic computer to have the fault codes cleared (if they exist). If it is a really severe case, then there is an additional patch loom that is recommended.
Haven't ever heard of an oil pump bolt coming loose, is this the subject of one of the recalls?
84 Rangie, 3 inch spring lift, 2 inch body, Megasquirted 4.6, R380, rear Maxi, 34x11.5 JT2s. Simex FM installed.