Fuel pressure should be 34-37psi so dropping to 29-32 would explain why it runs better with the return clamped. If the pressure rises with the return clamped, the pump is supplying enough pressure and the filter isn't clogged, so that would point to the pressure regulator.

Lambda sensors, if working correctly, should show 5V for lean and 0V for rich. However, a dead sensor will show a permanent 5V.

That sounds about right. They used to be around £250 plus VAT.

To get yours refurbed, send it to Jon https://www.ebay.co.uk/itm/404025564146. Any decent key cutting place will be able to cut you a replacement dumb key blade (they use a BMW blank made by Huff), I had a couple cut by my local Timsons but when I went in recently to get a spare cut for a new car I've got they told me that as a company they have stopped doing them as far too many didn't work. Land Rover could supply a genuine one but their website now shows them as no longer available so they may have run out, try asking at your local main dealer. Alternatively, Classic Rides North Wales (crnw.co.uk) can supply a non-flip remote key.

If the car locks and unlocks itself, that isn't anything to do with the key, it is one of the front door latches. The one that doesn't lock and unlock is the failing one.

Breakers tend to leave the carpets as they are such a pain to get out and not the easiest of things to store until a buyer comes along. A car that is ripe for breaking will usually have been neglected too so beige carpets are likely to be in much the same state as yours too.

Try giving Dave at East Coast Range Rovers a call on 07527 953807 and see if he has any or has a car for breaking that has some decent ones in it.

Have you had the plugs out yet?

If the cooling system gets pressurised, when you switch the engine off, coolant gets forced into the one cylinder with the leak, hence asking if it fires up on 7 as the one with coolant in it won't want to fire initially.

If you have a steam cleaned spark plug or it is pressurising and the pressure is staying, then not so much a slipped liner as a weep around the outside of the liner. If they have slipped you will hear it as they move up and down with the piston and whack into the cylinder head but with a weep they don't move, the combustion pressure gets into the coolant passages.

The genuine replacement O rings are the correct size and it is worth spending £3 each for genuine LR ones rather than saving a few pence on aftermarket which are also the correct size) but on the one I took out someome has used generic O rings that were the correct diameter but too fat.

Lez wrote:

I have a invoice in the file for new hevac o rings being replaced 10k miles ago

That proves nothing. A friend bought a car recently, the carpet was damp and most of the dashboard wasn't fitted correctly. Previous owner told him he'd recent had the O rings replaced but from the state of what we found when taking it apart, can only assume it had been done by a gorilla. O rings had been replaced with generic ones which were too thick so has been squeezed out of the grooves and were still leaking.

As the coolant passages run at each end of the heads, the usual head gasket symptoms don't usually happen so you won't see oil and coolant mixing, although you might see steam out of the exhaust.

Take the spark plugs out and if any look steam cleaned compared with the others, there may be a weep around the outside of the line on that cylinder. If when started from cold it initially fires up on 7 with the last one chiming in after a few seconds, that again would suggest a slight weep on one cylinder. The cooling system will pressurise when hot but if that pressure disappears once it has cooled down, then there isn't a weep. The top hose will get hard when it is hot but if it is then left overnight and there is no pressure there, you're OK.

There's lots of places where coolant can leak from, heater core O rings, the multiple hose joints, etc, so losing coolant is more often leaking rather than anything else.

Back end is quite different too. On the L320, the spare wheel hangs underneath at an angle (making it awkward to fit an LPG tank) whereas the L322 has a spare wheel well.

L322 is monocoque construction and doesn't have a separate chassis but the L320 does, so doubtful the towbar is the same.

Welcome. If the contacts on the switches inside the stalk get dirty, no matter how much you poke the sliding button, nothing happens. You can undo the 3 small Torx screws from the back and get in there with contact cleaner.

If that is all you have to worry about though you're doing well.....

Not sure what you are looking at but a leak from the valve cover would be far worse than that slight staining if that is what you ware referring to. What plugs are they? LR suggest Champions but modern Champions aren't the same quality as 20 years ago Champions were. Most of us run NGK plugs.

You've got that horrible SAI system to fight your way past too....

On a GEMS the fuel pressure regulator is purely mechanical (diaphragm and spring) so not going to be affected by the temperature sensor. What does the fuel pressure read when running and what does it read with the return clamped?

It will with them being that far out. Standard heights must be between 85 and 130 bits and ideally less that 8 bits side to side.

Been busy on the red one getting a working LPG system in it. It's been a bit slow as I've also been playing with my other toy, a 21 foot powerboat with a 200hp inboard engine, but that's a whole different story. It has had an LPG system on it previously but I doubt it ever worked properly. The tank, a piddly little 70 litre toroidal, was fitted the wrong way round so the pickup was at the front meaning that when getting low on gas and going uphill, it would stop if you put your foot down. A bonus was the tank was over half full but that did make it heavy so I had to lift it with my engine crane to rotate it. I've since arranged with Romanrob to take the tank that he is removing from his but the 70 litre one will do for the time being. The gas feed pipe was 6mm copper, marginal on a P38, and run down the RH side of the car. It appeared that the previous install had all been installed on the RH side of the car, wedged in amongst the fusebox, ECU, coolant reservoir and brake modulator. Quite why when there is an open space on the other side?

I'm putting a single point system in it. Even though it isn't the preferred modern multipoint, it's the same as on mine, I understand how to set them up and I've got spares. I'd previously sorted out the worst soldering I have ever seen in my life at the ECU, tidied that up and added the extra wires I needed for the LPG system. The ECU is fitted and wired, the switch installed and everything ready for the rest of the system.

I was at a memorial for a guy I used to work with yesterday (who, worryingly, was 4 years younger than me) but when I got home decided I'd get stuck in. I'd already fitted the vaporiser and filter/shutoff valve I just needed something to get the gas to them. Ran a new gas feed in using 8mm polypipe, far easier to work with than copper, clipped it all in place and got it connected at both ends. While I was under there, dragged out the old copper feed pipe. So today I picked up 10 feet of heater hose and connected up the coolant hoses, plumbing the vaporiser in series with the heater. Tried powering up the system with power to the shutoff valve disconnected so I could check the unions for leaks. No leaks thankfully.

All that left was the mixer and vapour plumbing. Fitted the mixer, connected the hoses and, after checking everything again, fired it up. On petrol it was still running the same as before, so, with the laptop plugged into the LPG ECU, switched over to gas and it promptly stalled. Started again and managed to get the revs up and at 2,000 rpm it was running smoothly but a bit lean. Adjusted the vaporiser until the mixture corrected and called it a result. Just got to tidy up the wiring and put it in corrugated sleeving.

At this point realised that it's almost ready for an MoT so did a few checks. It needs a pair of wipers, the rear washer reconnecting to stop the screenwash dribbling into the boot from the top of the tailgate and a set of tyres. The newest of the ones on it is dated 2003 and all 4 are perished and cracking. The rears are Pirelli Scorpions which go flat after about 3 days yet the Goodyear Wranglers on the front, despite being noticeably cracked, still hold air. I wouldn't fancy driving any distance on any of them though. Then it can go in for MoT and I'll find out what else it needs......

Don't buy the Dunlop branded one. They appear identical to the original Thomas (except the pump housing is plain alloy and not painted black) but don't seem to last more than a couple of years. Not sure who makes them but Dunlop certainly don't make compressors. If I needed one I'd go for a used original and budget for a new seal and sleeve.

The tick actually doesn't sound too bad. I've got 2 P38s (both 4.0) and have just sold a 4.6 and all do it to a certain extent. Mine was doing it when I bought it at 205,000 miles. At 287,000 the engine was completely rebuilt at V8 Developments and when refitted it, it still did it. As it sounded louder from underneath the LH side, I decided it must be from the torque converter or gearbox. At 454,000 miles the gearbox died so that along with the torque converter were replaced. Still does it, no worse, no better than it was when I first got the car.

If it works on newer Range Rovers and other cars as well it is probably something like the Snap On unit that most garages use which doesn't work on a P38 as it is too early. No point in replacing the sensors again unless you confirm you have a faulty one. Have you tried tapping them fully home?

A misfire on one cylinder when initially starting can be caused by a liner to block leak allowing coolant into that one cylinder but that would normally be accompanied by losing coolant and/or pressurising the cooling system. Start by taking the spark plugs out and seeing if number 5 looks any different to the others, if coolant is getting in there it will look steam cleaned or will have an orange tinge to it caused by burning coolant.