Diesel pusher making occasional "ch" sound while traveling

[bpaikman]

I have two questions -I'm not sure where to put them. i'll make two separate posts.
First question: Since we're having some airbag issues I'm a little sensitive now to any sound. Is it normal to hear a "ch" sound, somewhat like the brakes make, while traveling down the road, about every 15 to 25 seconds? We had diesel pusher for several years before this one, and I can't remember if this is normal.
We're having some issues with our airbag or solenoid.... and the freightliner guy I talk to on the phone suggested that the bags might be over-inflating, so I was thinking about that "ch"sound.

 

[Neal]

Normal - it's the air tanks popoff valve.

 

[CaptainGizmo]

That’s part of the air dryer system. There “can” be issues that will make that valve purge more often than it should. Water, bad regulator being a couple.

Some rigs, like our’s, will only give a hard pop-off when the tanks come up to pressure. After that, it’s rare I hear it.

 

[bpaikman]

Well, hmmmm posting next question soon

 

[High Desert]

With our rig, I will occasionally hear the pop off release. Nowhere near as often as you are hearing it on your coach.

 

[bpaikman]

Normal - it's the air tanks popoff valve.

every 15-25 seconds?

 

[Neal]

every 15-25 seconds?

No

 

[FloridaSon]

Agree with the above, every 15-25 seconds is not normal.

What do your air gauges read when the sound occurs? Does the psi increase or decrease after the “ch”? This my help isolate an issue.

 

[bpaikman]

Agree with the above, every 15-25 seconds is not normal.

What do your air gauges read when the sound occurs? Does the psi increase or decrease after the “ch”? This my help isolate an issue.

We're not driving right now... been parked for two weeks, but the gauges stay steady while we're traveling.
I'm looking at three clues right now, Which might be all or none related:
1... that "ch" sound
2. the porpoising that occurs occasionally ( we're trying to determine if there's a series of actions that leads to that)
3. the fact the equalizer does not dump air before leveling

 

[FloridaSon]

Gotcha, maybe the three issues are related?

 

[bpaikman]

I called Equalizer Leveling Systems and Freightliner today and they were not helpful.
I called Newmar and got a lady who offered to contact Freightliner with me on the line.
I wasn't excited about that suggestion because I had already called Freightliner and was told to look up the nearest service center.
We were finally connected to a man who seems to be extremely knowledgeable about the airbags. He offered reasonable explanations for the things we were experiencing, and tactfully suggested that our problem was operator error. He also mentioned, if we still needed service after trying his recommendations, which service centers might be easier to get into ...not quite so heavily trafficked by commercial trucks.
We are due to move on Sunday, and we will try his suggested procedures. If we are successful I'll post information about that.

 

[bpaikman]

Agree with the above, every 15-25 seconds is not normal.

What do your air gauges read when the sound occurs? Does the psi increase or decrease after the “ch”? This my help isolate an issue.

normal

 

[FloridaSon]

Operator error? How can that be when those systems should be basically automatic?

 

[bpaikman]

We were told by the Freightliner tech that the engine should be running and pressure normalized BEFORE raising the jacks, for proper inflation. We were raising the jacks before we even turned on the engine.
'We'll try this Sunday. He was pretty credible - outlining to us how all 3 of our concerns could be related to this.

 

[Gronk]

That sounds a lot like the purge valve on your air dryer caused by the air governor used to do way back when I was driving big trucks. Do you have an air dryer in your system? You should with air brakes.

 

[CaptainGizmo]

We were told by the Freightliner tech that the engine should be running and pressure normalized BEFORE raising the jacks, for proper inflation. We were raising the jacks before we even turned on the engine.
'We'll try this Sunday. He was pretty credible - outlining to us how all 3 of our concerns could be related to this.

Hmmm, while that’s good advice to always have your engine running for jacks and slide ops, it’s a bit misleading when it comes to “air purging” and jacks. I don’t know what rig you’ve got, but my guess is your jacks are hydraulic, so airing up is irrelevant in that reference.
The purpose of having your engine running is to support the electrical system. In our case, with a coach that’s based on air-bag leveling, then yes, we need to make sure we are aired up to achieve “Travel mode”.

 

[FloridaSon]

Captain Gizmo is right and I came across this post while searching my problem Equalizer:
Thread 'Starting the engine before raising the jacks'
Tip - Starting the engine before raising the jacks

In short Freightliner suggests doing this as it is faster to fill the bags.

 

[bpaikman]

That sounds a lot like the purge valve on your air dryer caused by the air governor used to do way back when I was driving big trucks. Do you have an air dryer in your system? You should with air brakes.

uhhhh

 

[bpaikman]

That sounds a lot like the purge valve on your air dryer caused by the air governor used to do way back when I was driving big trucks. Do you have an air dryer in your system? You should with air brakes.

We're planning on having some maintenance done later this fall.

 

[Gronk]

uhhhh

The compressor compresses the air (obviously....) and in doing so it can and will condense moisture in cooler fittings due to the air being heated by compression. The purge sound is the signal from the air governor that it is satisfied pressure wise and the purge is to rid the system of moisture. They look like this: Amazon.com : air governor