Berkshire Air Suspension Discharge

[GoneSouth10]

Question on a 2015 Berkshire 34QS, but other Freightliner chassis coaches may have the same situation/set up.
When I'm "aired up" to drive height, I notice that when I step on and off the coach step, I hear a short "PFSSSTTT" of air released somewhere in behind the right front tire (Note: This is different than the loud "diesel fart" that occurs when the air tanks reach pressure after starting the coach).
I always assumed this was just the air suspension "fine-tuning" itself (and before you even start typing the jokes, I'm only about 190 lbs, so emphasis on the "fine" . . . ) and I never really through too much about it. It doesn't do it when I step on and off the coach with the jacks down and fully set.
Fast forward to yesterday - I stepped off the coach, heard the familiar "PFSSSTTT", but then it continued (as in "pfffssssssttttttt" - much quieter, but continuous). Again, it appears to be coming from somewhere in behind the right front wheel (i.e., it's NOT the tire). No air discharge from any of the other wheel wells. It continued for several minutes until I had to leave, and then when I went back today, the coach had settled down to "non-ride" height and there was no discharge (at least no "pfffssssssttttttt"). Fired the coach up, aired up the suspension, and sure enough, back to the "pfffssssssttttttt" sound.
So the questions: First, is that "fine-tuning" normal every time I step on and off the coach while it's "aired up"?
Second, I'm assuming the quieter continuous "pfffssssssttttttt" is the air discharging out of the suspension system and I'm assuming that some discharge is normal (my coach would always settle down off of ride height, but usually it took a couple days), but is it discharged in one spot (i.e., behind the right front wheel) or all four locations? If it's a leaky suspension hose/fitting, is this an easy fix (e.g., soapy water to find the fix and then swap out the hose/fixture), or is there something else I need to be worried about?
Thanks in Advance!

[Igave]

I believe you’ve a valve stuck and allowing air loss. Behind that wheel is the purge lanyard and valve as well as the height adjustment setup. I’m betting your soap and water spray will find it and either a tightening or fairly Reasonable fix. And no, they don’t adjust every time someone enters or leaves. On my experience similar to yours, it was the height adjustment stuck.

[GoneSouth10]

Originally Posted by Igave

And no, they don’t adjust every time someone enters or leaves.

I didn't mean to suggest that they actually adjusted each time I stepped on or off the coach, but they just made that quick little pneumatic sound (maybe a half second long). Calling it "fine-tuning" was probably a little misleading, but just that short little "PFSSSTTT" - although I'm not entirely certain I'm spelling that correctly!
Also, when you say "my experience similar to yours", are you saying you also had the continuous discharge of air behind the right front wheel?

[Igave]

No, not the continuous discharge you are hearing. The settling of the airbag much sooner than it should. The leak in the system was the valve I mentioned plus another small leak at a joint on the rear. I didn’t have all the symptoms you’re getting.

[GoneSouth10]

Okay, I think it might be the same issue - my leak just became faster! (and audible)

[Oscarvan]

Don't panic just yet. I don't think there's anything wrong.

I hear the suspension letting off air when I step out. (175 pounds... ) And yes, sometimes it does it for a minute or more, very slowly.

Air up the coach and shut it down. Stay in the seat, don't touch anything. Max air pressure loss is 2psi per minute. You're not going to see that. If you do, there's a problem.

IF there's a problem and that's a big IF, and it's related to the suspension you're looking at the ride height valve. (This is where the pfffft comes from) IIRC correctly there's two in the front (one each side) and one in the rear. There's a small metal rod connected to the chassis which operates the valve as the height changes. Chassis low it lets air in, chassis high it lets it out. (pfffffffft)

Mine bleeds down to the stops in just under 24 hours.

[GoneSouth10]

Originally Posted by Oscarvan

Don't panic just yet. I don't think there's anything wrong.

I hear the suspension letting off air when I step out. (175 pounds... ) And yes, sometimes it does it for a minute or more, very slowly.

Air up the coach and shut it down. Stay in the seat, don't touch anything. Max air pressure loss is 2psi per minute. You're not going to see that. If you do, there's a problem.

IF there's a problem and that's a big IF, and it's related to the suspension you're looking at the ride height valve. (This is where the pfffft comes from) IIRC correctly there's two in the front (one each side) and one in the rear. There's a small metal rod connected to the chassis which operates the valve as the height changes. Chassis low it lets air in, chassis high it lets it out. (pfffffffft)

Mine bleeds down to the stops in just under 24 hours.

Okay, a couple of thoughts:
I'm good with the "Don't panic"! Particularly with the stepping off and on the coach - glad to hear that someone else has experienced that and that I don't need to go on a diet! (At least not for that reason . . )
I did air up the coach and probably had a slow bleed off of air (I'm watching the #1 and #2 PSI gauges on the dash) - not sure if it was under 2 PSI per minute, but I believe so (it was a pretty slow drop). I was focusing more on whether the two tanks stayed equal as they bled off, and they did. So I think I'm within standard operating parameters on that.
The thing that concerned me is that I had never actually heard the air bleeding out before - even though I knew intuitively that it was bleeding out (and 24 hours sounds about right, maybe a day and a half - never really concerned me, so I never really took notice).
I'll investigate a little closer next chance I have to crawl under there and see if I can locate exactly where the sound/air is coming from. There's no doubt that the compressor can keep up with the leak, so short term drivability is fine (e.g., if I have to get it onto a shop), but I wouldn't want to take any sort of long trip until I figure out exactly what the issue is - or isn't.
Thanks!

[Oscarvan]

Like I said..... find the little metal rod (about 6-8 inches long) attached to the chassis on one end and a valve body with air hoses attached to it on the other end. You've found the ride height valve. Now it's supposed to bleed into the atmosphere when the ride is too high (bag over filled) it has no way to put it back in the system under pressure. So hissing there is normal. Your judgement as to whether it does it too long. My money is on "no", but doesn't hurt to get close and personal with it for a bit.

[F.R.O.G.]

I had a similar situation many years ago on a trip to Alaska in the Sportscoach we had then. There's a valve at each wheel (or there was at that time) with a lever attached to the chassis. As the chassis tends to bounce, the lever opens or closes the valve to control the amount of air in the airbag. The whole device, not including the lever, was about the size of a couple of packs of cigarettes. The lever was about 6 to 8" long.


We heard air leaking every time we shut off the engine, and it was worse when I'd step on the stairs. When I started the engine, the air would come back up.

There was a rubber diaphragm on the valve, held in place by about four screws. With a gentleman who owned a small service facility in White Horse, Yukon, we eventually figured out that the issue was just that a couple of the screws had gotten loose. We tightened them, and never had another issue on that trip or for years afterward.

Not saying that's your problem, but the symptoms sound awfully familiar.

[GoneSouth10]

Originally Posted by F.R.O.G.

We heard air leaking every time we shut off the engine, and it was worse when I'd step on the stairs.

Yeah, but how much did you weigh back then??
I've identified one other type of sound that comes out when I step on/rock the coach, so I'm hoping the problem is very similar (somehow, I can envision the diaphragm you described causing that sound). Hopefully, it's an easy fix - after all, even I can operate a screwdriver!
Now I just need to crawl under and get dirty . .
Thanks!

[F.R.O.G.]

Originally Posted by GoneSouth10

Yeah, but how much did you weigh back then??
I've identified one other type of sound that comes out when I step on/rock the coach, so I'm hoping the problem is very similar (somehow, I can envision the diaphragm you described causing that sound). Hopefully, it's an easy fix - after all, even I can operate a screwdriver!
Now I just need to crawl under and get dirty . .
Thanks!

I've gained weight as a safety precaution. Fat people are harder to kidnap.

The valve in our case was near the left front wheel, and my recollection is that we got access to it by turning the wheels all the way to the right and coming in from behind the wheel.

[GoneSouth10]

Originally Posted by F.R.O.G.

I've gained weight as a safety precaution. Fat people are harder to kidnap.

The valve in our case was near the left front wheel, and my recollection is that we got access to it by turning the wheels all the way to the right and coming in from behind the wheel.

Well, now that I think of it, I've never been kidnapped, so that's working for me!

My issue is in behind the right front wheel, but the turning the wheel for access is a great idea (probably one I would have eventually come up with - after about 45 minutes rooting around in the dirt!! So obvious, BUT . . . )
Thanks again.