They do leak from time to time. May just be an o-ring gone or something come loose.
Remember you are having 4 bar of pressure in the system, so it really needs to be sorted out.
You'd be better off paying to get the dealer to accurately check the problem, rather than buying parts blindly.
A land rover diagnostic system would be better because you'll not only get manufacturer specific codes, but you'll get a more accurate diagnosis as it can be run with live/dynamic...
I expect the main input seal to the gearbox has been leaking. This may have been contributing to the clutch failure as it contaminates the clutch and flywheel.
Did you get it sorted?
Get an independent to do it. Anyone with IDS/SDD should be able to do the download. Autologic users can also do it provided they are still paying for their subscriptions. For £60, I'd personally be giving you the option to have a load of updates done while SDD is still connected to the vehicle.
We had one in earlier in the year. The cam driving the fuel pump broke close to the pump. We have yet to tear down the unit to see if there were any other issues, but I do have the complete unit on a pallet at the moment.
The engines are expensive new/reconditioned - £5644 + VAT for a...
The intercooler pipes are quite long and sometimes collapse under hard driver demand. Could be this causing it. Under normal demand it will remain open.
Get a Classic - Catches people's eyes, cheap parts, and a DIY vehicle. Otherwise get an L322. Don't bother with the p38 - I owned one for 8 year and could have purchased a house with the amount of money I spent keeping it going.
If it's a pre 99MY with GEMS engine management (rectangular inlet), then the standard blue ethylene glycol is all that is required.
If it is a post 99MY with the Thor/Bosch engine management (banana inlet manifolds) then you should use the Havoline XLC which is an organic technology coolant.
From experience, the Paddock discs tend to rust really badly due to the poor metal. I binned them after a year and purchased some much better quality ones which rarely had surface rust on them.
Get a set of either the Allmakes4x4 standard discs, or the OEM Delphi/Lockheed discs. Usually...
When buying a Disco3, don't buy one with miles on it, and don't buy one with the manual box.
Also, the 105k mile service is both the cam belt and the HP fuel belt replacement. The body will have to come off to do this, so the service is going to exceed £1000 in most cases. If you are going...
The Terrafirma stuff is excellent quality.
The standard Terrafirma springs give a 1.5 inch lift anyway, so this may be the way forward? The big bore dampers are awesome. Seriously good quality heavy duty units.
If you want a contact, try Dan at Brookwells - Land Rover Parts, Accessories...
If you just wanted a mild change, get a good remap done as in one done by a reputable company like Alive Tuning. The software map can be programmed to keep the EGR closed during normal running conditions, so this is a software thing, not hardware like Td5. Start here.
If that's not enough...
The obvious call is electrical, but how about an injector seal problem?
When the diagnostic check was done, was it possible to monitor some live data while the engine was running? If not it would be worth finding someone who has Testbook/T4.
You could try checking the gearbox oil is OK and not contaminated or incorrect. I've seen a few do this sort of thing with either water contamination or incorrect oil, so as this is a recent purchase which you've probably no history on, may be worth a check first?
The sender unit is part of the fuel pump in the tank. The cheap ones last 12 months but cost £150, the Genuine ones are 220ish. VDO supplied units are OEM/Genuine spec.