Booking the car in to Ian Barclay in Birkenhead, who come very highly recommended, to see what they can diagnose. No doubt it'll take them 5 minutes to find the fault !

Will report back after the 21st April - they're very busy !

An update !

Rebuilt my front valve block, connected all the pipes and had the previous noted problems. Booked it into Ian Barclay who connected it up to their system and identified the system losing pressure on the near side circuit.

Re- booked it in to have another look yesterday but unfortunately they didn’t have a lift free, so couldn’t do any work on the car.

At this point it was hissing out air from the valve block area, so as it was a lovely evening I decided to have another look myself.

I discovered that air was actually coming out of one of the torx head screw holes that hold the top and bottom of the valve block together.

I realised that the only way that can happen is if air is getting past a seal. Although I had a spare, fully rebuilt valve block I wanted to know what was wrong, so opened the valve block up.

Turns out I’d missed installing two of the seals on the left and right solenoids. No wonder it was leaking and surprised only one side was coming up on the LR system.

Put the seals in, re- connected and now have it on extended mode overnight, with the fuse pulled.

Having gone from the front fully dropping in 10 mins, it’s now sat at full height for 3hrs or so, so fingers crossed it’ll still be like that in the morning.

Kicking myself for being an idiot in the first place, but also quite pleased I have hopefully sorted it myself.

Now have to sort an issue with getting the downstream O2 sensor out, which is apparently jammed in.

Quite literally an overnight success.

Didn’t drop a single mm, so finally confident it’s sorted.

Please for u

Great. Well done and thanks for the details around the issue and repair.  Barrie.
2017-Jan 2024: 2005 RRS 2.7TDV6. Best car I ever had - until now!
Current: 2018 Ford Ranger Wildtrak 3.2

My pleasure - what it’s taught me is that the suspension isn’t rocket science. There’s a pump, a tank, pipes, valve blocks and air bags. If you can isolate what’s causing the problem then generally it’s an easy fix.

As long as you don’t forget to fit a critical seal or two of course.

4.2 SCs are more involved than the diesels as the front valve block is behind an auxiliary radiator and then a plastic shroud, with tricky to locate 8mm bolts, but once you’ve done it once it’s a breeze.

And still it holds pressure without dropping a single mm, even after a week.

The car goes in to my friendly local garage at the top of the road tomorrow, to get the downstream O2 sensor replaced. They’ve got one of those fancy Ed China style induction coil heaters, so should be able to get it off a damn sight easier on a lift, than I would with axle stands.