Sounds like your engine running on its own oil, and you are very lucky that it slowed down to idle speed. This problem is potentially fatal to your engine and is caused by excessive crank case pressure caused by cracked pistons, a cracked block or badly worn rings or bores. There are ways to fix the problem, but unfortunately it is is a known problem which tends to kill most early 19J turbo diesel engines. Later turbo diesel engines (before the 200 and 300 tdi) were better, because Land Rover redesigned the block somewhat to cope with the excess heating problems.
Try this test:
Disconnect the engine breather pipe from the oil filler cap to the air intake manifold, so that there is no oil being fed into the bores, and let the engine run up to temperature. Once the engine is at temperature, have some one rev the engine slightly whilst you place your thumb over the oil dipstick tube for about five seconds. Release your thumb, and if there's a lot of pressure, or your engine physically launches oil out at you, you are looking at a strip down or a replacement engine.
If there is no pressure, it could well be the turbo that has gone. There is a hell of a lot of oil lubricating the bearings under a lot of pressure and if it leaks, it will be blasted into your engine and burned!
If there is pressure, the best thing to do is remove the head and examine the top of the pistons. If there are any visible cracks, they are more than likely the cause of the problem. If there are no cracks, I would expect rings or worse, possibly a cracked block which is not worth the time or the expense repairing.
I hate to sound so negative, but it is a well known about problem which will (if it happens again) destruct your engine. If you are still driving your land rover, and you notice the engine starting to rev its nuts off again, immediately whack it into fifth and slam the brakes on in an attempt to stall the engine. You must stall the engine, because turning off the ignition at the key will have no effect.
If you would like to know more or investigate and potentially fix the problem, just ask! I'm based in Leeds if you would like me to come and have a look at it or help you get at the pistons. My summer holidays are coming up within the next 3 weeks and I'll have nothing better to do!
-Pos
