Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: bigdog on May 11, 2022, 04:40:22 pm

Title: Air pressure drain while driving
Post by: bigdog on May 11, 2022, 04:40:22 pm
Given that I just had my foot valve replaced and last season it was the ABS valve and have always had my air tanks drain off quickly since buying the coach.

So I have a question for the group. Baring any glaring leaks. How much does everyone's air tank bleed off pressure when driving down the road? With the fairly soft suspension of the U320 and 8 airbags. How quickly will the air suspension draw down the air pressure. I drove down the road for about 10 minutes and lost about 5PSI and a bit faster on a rougher side road. I would like to have a ball park range of what folks lose and how quickly

Title: Re: Air pressure drain while driving
Post by: Protech Racing on May 11, 2022, 05:22:28 pm
Sounds about right .
Title: Re: Air pressure drain while driving
Post by: Doug W. on May 11, 2022, 05:24:52 pm
I would say what you are experiencing in air loss is quite normal. Seems like mine does about the same. Air bags are always compensating for road conditions.
Title: Re: Air pressure drain while driving
Post by: bigdog on May 11, 2022, 08:50:01 pm
Thanks guys. I figured I might be in the ballpark.  I hope it stays that way.

Next project is to get my retarder working reliably. Right now it will work and then stop working and will not come back on until I stop and turn the coach off. Thus resetting the system.
Title: Re: Air pressure drain while driving
Post by: Doug W. on May 11, 2022, 09:03:07 pm

Next project is to get my retarder working reliably. Right now it will work and then stop working and will not come back on until I stop and turn the coach off. Thus resetting the system.

May want to pull the codes on Allison before you turn it off, see if anything comes up.
Title: Re: Air pressure drain while driving
Post by: bigdog on May 11, 2022, 10:07:57 pm
May want to pull the codes on Allison before you turn it off, see if anything comes up.
You press the up and down arrows at the same time while running in neutral, Correct?
Title: Re: Air pressure drain while driving
Post by: Doug W. on May 11, 2022, 10:31:03 pm
You press the up and down arrows at the same time while running in neutral, Correct?

Yes pressing both arrows down twice will bring up codes than press mode button for d1 thru d4 codes. Holding the mode button down until you hear a beep will clear codes.
Pressing both arrows once will bring up oil level while at idle and level.
Title: Re: Air pressure drain while driving
Post by: wolfe10 on May 12, 2022, 08:36:27 am
And, the engine does NOT need to be running to check for codes.  Ignition on is all you need.

Yes, to check transmission fluid level the transmission needs to be warm (like 50 highway miles) and engine running.  To check, with transmission in neutral just press the up and down arrows at the same time ONCE.
Title: Re: Air pressure drain while driving
Post by: bigdog on May 12, 2022, 11:51:18 am
Thanks Doug & Brett. Downloaded the code chart to my laptop. So when it goofs up on our trip tomorrow I'll stop and write it down.   
Title: Re: Air pressure drain while driving
Post by: D.J. Osborn on May 12, 2022, 12:11:36 pm
I've never really put a timer on it but I would guess that in normal driving my air pressure goes down about every 15 minutes or so and then the compressor builds it back up. I think it's normal operation.
Title: Re: Air pressure drain while driving
Post by: wolfe10 on May 12, 2022, 12:45:21 pm
I've never really put a timer on it but I would guess that in normal driving my air pressure goes down about every 15 minutes or so and then the compressor builds it back up. I think it's normal operation.


Yup, normal.

And air is used more/cycles more frequently on rough roads and when using service brakes.  Again, perfectly normal.