If you can power it, check the LM2931. It's a 5V regulator so will have full battery volts on one pin, centre pin will be grounded and the other pin should have 5V on it. Very carefully check the feed through holes as it's a double sided PCB. If any look even slightly iffy, push a piece of bare tinned copper wire through and solder it on both sides of the board.

Interesting although I've never tried it. Pulling the timer relay (or fuse 44) is a good way of isolating which corner has a slow leak but I can't see the point in removing the timer relay and replacing it with a 4 pin. If you habitually park on very rough ground it might reduce the load on the compressor marginally but when it self levels it drops 3 corners so won't be taking anything out of the reservoir.

Yes. The timer relay is energised all the time the ignition is on so supplies power to the EAS ECU. It then also wakes up every 6 hours or so to power everything up for the self levelling. Putting a 4 pin relay in means it is only energised while the ignition is on, so no wake up and self levelling but also no diagnostics. Fuse 44 supplies power to the ECU via the timer relay contacts (or via the 4 pin relay) so with that pulled the timer relay will still wake up and energise but won't have any power to switch. Easier than grovelling under the seat trying to pull the timer and far easier than trying to get the thing back into it's socket which you will invariably have pulled off it's mounting point so it is now floating around on it's wiring.

You obviously won't be able to connect diagnostics with Fuse 44 pulled as the ECU won't be powered.

Unless there's a huge ridge, which you would be able to feel anyway, it won't damage the rings. Once out, check the bores for round to make sure they aren't going oval but if you can still see the hone marks, that's pretty unlikely. Same with the crank journals. Check for round and any scratches but again, unlikely to need a grind unless the engine has been really neglected. New piston rings and big end and main bearings should be all you need. When my engine was rebuilt at V8 Developments, they used the original pistons as 4.0 litre pistons are about 4 times the price of 4.6 ones. As Ray said, the rings do the work, the pistons are just something to put the rings on so can be reused as long as they aren't damaged.

Beowulf wrote:

• The pistons can just be tapped out the top of the engine block? How do you remove the carbon ridge? Using my finger nail I don't really feel any ridge.

If you don't feel a ridge then do as the book says, and just tap them out. Make sure you've got a ring compressor for when the time comes to put them back. That's one of those tools that gets used so rarely you can never find it when you need it but find it a couple of days after you've gone out and bought another.

• The piston connecting rods have 12 point bolts where they connect to the crank. A 9mm is too small while a 10mm was a bit loose. Are these imperial? Tomorrow I'll scout for a 3/8" 12 point socket.

GEMS engine is all Imperial, Thor is a mix of Imperial and Metric, so quite possibly the big end bolts are Imperial.

• Regarding removing the crank, the six hub aligner screws are really on there. Removing them is made more difficult by the crank not being locked. On page 36 of the Engine rebuild manual, where it covers removing the crank, step 4 says to "Remove 6 socket head cap screws securing hub aligner to crankshaft, remove hub aligner." I was thinking it wise to have the machinist check the crank for wear and balance but should I bother removing this hub aligner? It isn't necessary to remove the crank from the block. One could stick a piece of wood in the crank galley to lock the crank against assuming that won't somehow damage the crank. That's doubtful as the crank looks extremely robust.

They will have been put in with Loctite when the engine was assembled so will put up a fight. Choices are to jam a lump of wood in there to stop the crank turning or leave them where they are, as you say, crank can be removed with it still attached.

• The rebuild manual doesn't mention a specific order that the main bearing bolts need to be released by. Ditto for the big end bolts I mentioned previously.

I don't think it matters to be honest. The crank is so stiff you aren't going to bend it. Sit it in place on the bearings, drop the caps on and torque them up (remembering to make sure it still turns after doing each one).

Here's a few more images just because...

I wanted to give a mod the fun of correcting the links so they showed properly.......

Now that's one I can answer, yes the nav does talk directly to the DSP amp. Input from the nav is on a pair of wires, Yellow/Orange and Orange/Yellow on pins 18 and 19 at the amp. It also has a Mute line on a Grey/Orange wire on pin 7. I think all the illumination is bulbs, it is on the earlier Clarion anyway.

High power one is only a good idea for the compressor relay, timer only powers the ECU so doesn't need a high power one (fused at 10A). Or just pull Fuse 44 which supplies power to the timer relay contacts so it will still wake up and energise every few hours but won't do anything as it will have no power to switch.

Not when towing though I bet....

I actually followed a Polestar2 the other day and wondered what the hell it was. Figured it was an EV due to the lack of tailpipes poking out the back but hadn't a clue what it was. So memorised the registration number and looked it up on the DVLA site as soon as I got home. Not a bad looking vehicle actually.

As long as it isn't cracked it should be fine. I tend to put a thin smear of blue Hylomar around the waterways at each end anyway.

Definitely looks like ATF to me (nice clean ATF at that). Could it be that you have a leaking cooler hose and it is spraying it onto the side of the engine and dribbling down?

Ascot on Triple Sports, 8J x 18 so running the standard 255/55 x 18 tyres while the Ex-Plod is on Futura which are 7J x 16 so rather than running the usual 255/65 x 16 that all the other 8J x 16 wheels took, runs on 235/70 x 16 tyres (more commonly a Discovery 2 or late Range Rover Classic size). Only a few of the earlier, usually base model, P38s were fitted with the 7J x 16 wheels but plod obviously wanted to save a bit of money when they specced mine.

Triple Sport (see https://www.cxmdunord.nl/rims-land-rover/) same as I have on the Ascot. Not Discovery but actual Range Rover wheels, just not particularly common.

I have a feeling at if the laptop is booted with the cable already plugged it, Windows detects it as a mouse or something like that. I boot up the laptop, start the car, then plug in.

I've seen 3 different types of diaphragms from different rebuild kits, so it's quite possible you've got an iffy one. More likely that than anything you did, if that was the case I'd expect it to not work from day 1.

Altering the delay never seems to do much. Go into the Comm port properties and drop the baud rate to 4,800.

With you pictures you are doing it right but then editing the link. What should appear is;

Looking at a spare valve block I have here, it appears the PRV is just that, a passive device. No electronics attached to it, just a brass valve.

There's 2 versions of the 4HP22/24, the 4HP22 as fitted to the Classic and the 4HP22EH as fitted to the P38. The EH version is electronically controlled.

On the underside of the valve block, you've got two solenoids (Front Left and Rear Right) but there's also the Pressure Relief Valve and Pressure Switch. Highly unlikely a solenoid would suddenly start leaking that much air out so it could be either of the others.

Only thing that would be of concern for me is that it absorbs water so it might not be too good when I come to use it after it's been in the tank for a few months. Maybe I should just pump it out every couple of months and use it in the lawnmower?

If it won't connect, drop the baud rate to 4,800. Had to do that when trying to use the RSW software on a Classic although works fine at 9,600 on mine.