my 07 bleeds down when it sits for a few weeks. I start it and its fine rising right back up. If it's driven regularly it doesn't do this.

 

Army this happens overnight or within a few hours. Ill crank it back up and it will rise back to level and then it will run the compressor for 2-3 mins to refill tank. I don't know if I should go chasing around the vehicle with soap and water. replace the valve block or send it to the junkyard!!!

 

Then assuming you have no warnings on your dash I would start trouble shooting the system to narrow it down as to the culprit. With the information I have currently I would start looking at the front first for my issues but that is on extremely limited info.

Trouble shooting is king on these trucks, throwing parts at them or making assumptions is both costly and typically ineffective.

 

Have you replaced the old desiccant and installed a compressor rebuild kit? (old stuff will turn to powder and ruin things)
Replaced the Dryer or at least just the end cap with new or metal version? (can crack between hose connectors, easy soap test)
Cleaned/rebuilt your front and rear Valve Blocks? (powder ends up here and keeps from sealing 100%)

I recommend all of the above - then report back
I get your frustration, but junking it over a few hours of known fixes seems extreme

 

As has been said above, finding the fix can take time, and not necessarily expensive new parts. For the suspension sinking, let the vehicle achieve a stable normal height, then switch it off. Remove fuse 26 in the engine compartment (which will stop the vehicle trying to find level) and report back. The valve block rebuild is a $25 fix, and about 2h of your time done very slowly with breaks for tea. I'd start there. There are plenty of good links to the job on the line. Here's one:
The rear valve is a **** to do, hence most start at the front.

If you find white powder in the valves, you should follow the advice and replace the dryer. At least.

You can check the transmission fluid level without any special kit or even a ramp. Just raise the vehicle to offroad height, place a couple of axle stands under the frame, switch off, climb under it and remove hte heat shield (4 x 8mm bolts I think), Identify the filler plug (hard to see, quite high up, right hand side of the casing) and using a breaker bar (not a ratchet) and 8mm allen drive, crack it open (it can be extremely hard to move, hence the long breaker bar). Start the car, leave a door open to stop the car leveling (make sure your axle stands are in place) and open the fill plug. If nothing comes out, add fluid until you get a drip back and you're done. But make sure you use the correct fluid if you want to look after this thing - should be Lifeguard ZF 6 in the US, I think. Not the LF8, which is for the LR4 8 speed. It isn't cheap fluid.

 

@Globetrotter448 Is that a way to legitimately get the fluid level right? I thought it had to be on level ground?

 

Yes. Do what I said above if you can get under the vehicle with it in off-road height. (Use stands; leave the passenger door open etc). Or use a ramp. The vehicle must be level to check the fluid and the fluid temp needs to be warm to get the level correct, so engine running and transmission temp around 30-40 C is good. The correct level is reached when you’ve filled it and a tiny seep pops back out. Put the filler plug in at that point. But the vehicle must be level.

 

I understand what you are saying but you are keeping the vehicle level.

He is saying put the right front tire only on a ramp which in my mind takes the vehicle well off of level. That is what I'm trying to understand

 

The problem is that the best way to do it is on a hoist. Yes on flat ground, in off road height it can be done unless your are a rotund person like me. If you put both front wheels on ramps the level will still be out slightly as it will be tilted rearwards. The amount it is out when one wheel is on a ramp is compensated by being tilted rearwards and also tilted sideways so for 90% of cases it is satisfactory. Hoist is best.

 

If you want to do the level check properly, the vehicle must be level and the oil temp needs to be around 38c. How you level the vehicle is up to you. A lift is indeed far better as it gives easy access. Off-road height is a painful way to do it. There’s barely any room to move and you will burn your arm on the cat at least twice.

ISTR there’s a good Atlantic British vid on this. The oil change is easy on the V8 using the pump out/push in method via the side of the rad. The hardest bit and the most messy is getting the level about right.

that said, I don’t think it’s an exact science so don’t worry overly much of the vehicle risk at a bit of an angle.