My firm has got this well weary 21 year old Volvo which I trundle about locally delivering and collecting forklifts. It does the job pretty well most of the time but just recently it’s become uppity on the reliability front.
Most of the problems are now under control but the elephant in the room is the rear suspension - I have changed the solenoid valve which has stopped the truck dumping all its air when the ignition is off but the problem now is that even with 8 to 8.5 bar the back end takes about 15 mins to get off its stops - longer of course if loaded. This has been happening on and off for about two months. However when the bags are full enough to set sail when you stop on site 20 mins later the suspension will raise and lower very smartly even after loading.
I have changed all four bags and was met with a half cup of water in each - subsequent inspection of various fittings show dampness throughout which is NOT a good thing obviously so a receiver/drier filter will be fitted.
In front of the rear axle are two tanks which I presume are reservoirs for the system - the unloader valve will kick in but these two certainly don’t have equal pressure as the rest of the trucks system…
So my question is - is there a valve in line from the main system or some other gizmo which is stopping the suspension tanks charging normally?
I’m pretty sure that is the problem - over a few miles eventually enough air gets through and and the wander control works well.
However, there’s more unfortunately - the nail goes for it’s Annual Inspection a week today and it’s being presented by a non Volvo dealership whose enthusiasm for the lorry is paper thin as it is.
The problem is not the braking system or the ability to get the air up - it’s just this reluctance to lift. It still loses a little air when the ignition is off but nothing like it did before and it’s never been a problem for me because I usually leave the engine running when unloading/loading anyway having to quite often use the winch. (I have to say here that the air always stays up at all times when driving, sitting in jams etc)
The pre-inspection report isn’t too bad at all and I feel I have covered the two or three fail points - there’s only two adviseries also and one of them was the bags. Could be a lot worse.
Last question is - even though the truck is showing good air pressure can it fail because of (possibly) the suspension playing up on test - as I’ve said it shouldn’t but then I’m not the one presenting it - I wish I were.
Our local Volvo dealerships are unhelpful frankly but as I’m going to present myself at reception tomorrow they won’t be able to goof me off with the old someone will call you back bollox.
All I need is help from someone who knows these trucks, a ten minute chat. I’ve spent hours on line but to no avail.
Thanks in advance and thanks if you’ve made it to this sentance 
PS Why do I stay one may ask - well the yard is 7 mins away from my house, it’s all day work no evenings or weekends and I get paid very well - lets say about a fiver an hour more than Downturns or Stobrats and apart from the truck no hassle. Frisbee style tacho, old school defect book and never questioned about the time to do a job - just left alone to get on with it.