Volvo air & suspension problems

Have a 2015 Volvo VNL w/D13 & a 13 speed. I’m having 2 issues that are getting me frustrated, mostly because our mechanics seem to think problems like this aren’t a big deal.

First issue is low air system pressure. The gauge on both tanks will only go up to about 105-110 psi max but 90% of the time they are both dead on 100 psi while driving down the road. Compressor kicks in just below 100. I’ve looked for an adjustment but cannot find one & have also heard there is no adjustment. What needs to be changed or replaced to get air pressure up around 120-130 and stay between 115-125 psi? Also, both air tanks lose every bit of pressure in about an hour & the rear air suspension deflates completely.

Problem # 2- Truck started riding really rough & seems to be swaying a lot going down the road, especially in curves. I’m almost always fully loaded with max weight of 80k gross. Air system pressure stays right around 100 psi. I had all the shocks changed about 20k miles ago including the cab shocks. That helped quite a bit but still isn’t right. It feels like the truck has a leaf spring suspension rather than air ride. It’s got the Meritor axles with Volvo air suspension. I could be imagining things, but I swear when I hit the dump valve for a few seconds while driving down the road and then release it and let system build back up with air, it seems to smooth out a little bit...atleast for a few minutes. Also, as mentioned with 1st problem, I’m losing air pretty fast with the engine off and once pressure falls below 60 psi the air bags will deflate completely.

Anybody ever experienced these issues with their trucks? Any suggestions would be greatly appreciated, thanks!

 

My truck doesn’t have the suspension air gauges so I don’t have a clue what pressure is actually in the bags. The truck currently has 455k miles and I’ve had it since new. I never thought about cab bushings... I do know that the rubber bushings in fender skirt brackets are wore out and letting the skirts wiggle around. Worn out cab bushings will cause a rough ride and massive sway & leaning? It fills like I’m gonna flip over going around a little curve after I’ve already slowed down to like 55 mph! I remember when truck was new, I could hammer down around curves... like 65-75 mph. Forgot to mention, cab is also leaning to the left towards drivers side. Where are these bushings located? And where is the adjustable air pressure governer located? Thank you all so much! I appreciate it

 

It’s a 630 midroof. Well, VNL64T630 to be exact and it has the 12.5k twin-leaf spring front suspension with regular gas shocks & drum brakes. No air ride up front. I thought it was a Volvo brand axle, but I could be wrong.