PSI

[wfalch]

I happened to be sitting in the front yesterday and noticed the the PSI is 0, thats zero. We took the couch for a drive on 12/2/2020 and of course before we left we heard the whoosh. The last time since then that I can remember it was about 60 or 70. So, it's seems like something is wrong, your help on this forum has been invaluable, once again I am looking for your help.

[Skip426]

Going to need some clarification.
Is this an issue with the coach air tanks , suspension and air brakes?
Do you have, two air gauges? Are both reading zero?
The pressure now is zero , after sitting for five weeks?
Or running the coach today , and the pressure won’t build?
The last time you ran the coach, pressure would only build to 60/70 psi?

[CountryFit]

Skip asked all of the good questions . On our coach after a week the only gauge reading remaining is fuel level (while power off).

[wfalch]

Sorry, I get excited about these things:
I believe that the PSI gauge is only for the ABS brakes.
There are 2 needles green and orange both are at 0.
The pressure is at 0 five weeks after we started the coach and it was full with a swoosh.
Coach is leveling fine couple of times a day.
Not all gauges go to 0
Have not started the coach today, figured I should state the issue b4 starting.
Have I answered al your questions.

[TonyDi]

If your pressure will only build to 60-70 you have to have an air leak. More info will help us find out what is going on.

[twinboat]

If your not running the engine and just using air for leveling, 60 to 70 PSI may be all you need. That air is only for the suspension.

If you start the engine, the 2 gauges should climb to 120+ PSI and then you will hear the air dryer purge.

If the gauges stay at 60 to 70 PSI, with the engine running, there should be a loud buzzer and low air warning light. You should not a temp to drive it like that.

All air systems loose some air. If it holds longer then a day, without running the engine, you have a good one.

[wfalch]

Well it did build to over 125 which is when you hear the swoosh. It usually goes down after we drive and park it. Pretty sure it was down to 70, cant really say when, like I said it always goes down, very surprised its at 0. It's been parked since 12/2. The only thing I know for sure is where the 2 valves are to let water out. I also know where where the compressor is in the run bay.

[Mudfrog]

Originally Posted by wfalch

Sorry, I get excited about these things:
I believe that the PSI gauge is only for the ABS brakes.
There are 2 needles green and orange both are at 0.
The pressure is at 0 five weeks after we started the coach and it was full with a swoosh.
Coach is leveling fine couple of times a day.
Not all gauges go to 0
Have not started the coach today, figured I should state the issue b4 starting.
Have I answered al your questions.

Firstly, I'm not familiar with the air systems on diesels so I might be way off base. If the coach levels via air bags, then it sounds like there's a pretty good sized leak if the coach is doing it a couple of times a day. Would think that would deplete the air tank fairly quickly.

[deandec]

If the gauges for your air tanks show 120 psi shortly after starting the engine (allow 3 minutes) then your engine air compressor is ok.

With engine off and sitting still, if the psi declines in a few hours to 70 psi, you probably have an air leak. My rig takes at least 2 weeks to lose that much air pressure.

Your 12vdc electric auxiliary air compressor will try to correct air leveling problems when the air bags lose air but likely not completely up to the task if the leak is large.

You could have an air line fitting leak, a hose leak, or an air bag leak. Possibly it is the air leveling adjuster itself that is leaking.

I took my rig to a Kenworth dealer for the same issue last year. One new leveling valve and problem was solved.

The valve cost about $100.

The labor cost is dependent on how difficult it is to find and fix the leak.

Having the rig on a lift saves money in finding the leak.

(Note: I recommend that you execute the DOT pre-trip air brake tests to learn how your system is working. Professional drivers do this at the beginning of their trip to avoid unnecessary roadside repair costs or collisions.)

[gnvrvin]

Wally,

Yup sounds like an air leak somewhere

Start the engine let the air build back up and listen for the whoosh (Air dryer purging) could take more than 3 minutes if everything is empty, give it time

With a leak like that your main airbrake compressor that is mounted to your engine would more than handle it while traveling

The little compressor in the bay under the driver is for releveling the coach while you are parked

Here is a video on how to check your air brake system:

https://www.youtube.com/watch?v=MbnVGWqDHIU

Dont forget to chock a rear tire prior to starting and remove same before last step

Lets see if others chime in on how much air they loose while parked.
We loose about 50PSI after a few weeks so drops to 70 PSI I usually like to start the coach up and rebuild pressure and let the system purge and shut her off every few weeks anyway

Happy New Year to you and Elta Mae,
greg

[TR4]

If your at zero after a month you have an air leak. My tanks drop to about 70 psi after 6 months in storage.

On my coach the air gauges read pressure in the primary and secondary tanks which are fed by the wet tank. Check valves separate the wet tank from the primary and secondary tanks. Could be a bad check valve, bad hose or leaking fitting.

Bill

[wfalch]

Ok, started the coach and the PSI gauge went to 125 and we heard the swoosh. Before I shut it off we put it in travel mode and then we leveled the coach. Shut it off, I have heard it's not good to idle for long periods. Now we will monitor the PSI gauge. The one thing I noticed that was suspicious was the oil pressure gauge went to 60 and stayed there.

[twinboat]

Originally Posted by wfalch

Ok, started the coach and the PSI gauge went to 125 and we heard the swoosh. Before I shut it off we put it in travel mode and then we leveled the coach. Shut it off, I have heard it's not good to idle for long periods. Now we will monitor the PSI gauge. The one thing I noticed that was suspicious was the oil pressure gauge went to 60 and stayed there.

60 PSI oil pressure is normal. After a hard run it may drop at idle, but bounce back to 60 while driving.

[96 Wideglide]

Oil was cold and thick. If you had left the engine running at hi-idle for 15 or more minutes, you would have seen the oil pressure coming down.