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Topic: We have a situation. Cycling air pressure  (Read 565 times) previous topic - next topic

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We have a situation. Cycling air pressure
Rolling down interstate 65mph and both air gauges are cycling. They pump up to 120 and after 30 secs, they slowly go down to 100psi, then pumps back up! Normal operation? Possible leak? Suggested actions.
Thanks

Re: We have a situation. Cycling air pressure
Reply #1
Yes, something is wrong.  That is way too fast for air pressure to cycle from cut-out to cut-in.

Could be an air leak, could be a defective air dryer, etc.

But, DO diagnose and fix this.

Re: We have a situation. Cycling air pressure
Reply #2
Hi John,
When you come to a rest area or someplace you can safely park, leave the engine running and lift your engine hatch. When you hear the compressor kick off shut off the engine from the rear and listen for air. Most likely the dryer, but...

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Re: We have a situation. Cycling air pressure
Reply #3
We stopped at a truck stop. It was chilly this morning, high 30s. Any chance the temp affected it? Cycle times have increased with no action from me. Cycle time of the compressor is now about 4.5 minutes. What is normal cycle time?  Thanks all.

Re: We have a situation. Cycling air pressure
Reply #4
Cycle time depends on air use of suspension and brakes.  No average time is recommended as a diagnostic tool.

If suspension is aired up and you are not on the brakes, while parked, you could well more than make it through happy hour before it...

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Re: We have a situation. Cycling air pressure
Reply #5
If you are stopped then there is no up and down wheel movement from driving and less air gets used by the ride height valves. A rough or uneven roads will use more air.  Do your air pressure gauges show pressure when you tuen the ignition off? ...

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Re: We have a situation. Cycling air pressure
Reply #6
Ok, after sitting 15 min with engine off, the top air gauge has held steady at 110 psi, bottom air gauge has bled off 4 pounds to 106.

Re: We have a situation. Cycling air pressure
Reply #7
First things first, Navybean, welcome to the list, and congratulations on purchasing your last motorhome first.
Secondly, I imagine it's tough your not being able to hand your new-to-you Foretravel off to the crew chief with a list of repair...

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Re: We have a situation. Cycling air pressure
Reply #8
Funny thing watching the air gauges cycles, took a bird strike to the right windscreen! No damage just a loud thud and back to watching the gauges!

Re: We have a situation. Cycling air pressure
Reply #9
Seems to be acting normal now! Will let you know down the road how it is going.

Re: We have a situation. Cycling air pressure
Reply #10
There may be some time delay but this is mechanical system. Tire goes up relative to coach, ride height valve lever goes up which signals the level manifold to add air to the air bag to push the coach up.  On a smooth road not much happens. On a...

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Re: We have a situation. Cycling air pressure
Reply #11
John,

Again, your symptoms suggest an air dryer needing replacement/complete service.  Put that on your short term "to do list".

My recommendation is a FACTORY (i.e. the factory that made it) reman.  Everything but the metal housing would be brand...

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Re: We have a situation. Cycling air pressure
Reply #12
Thanks all! My blood pressure is getting back to normal.

Re: We have a situation. Cycling air pressure
Reply #13
John,

Again, your symptoms suggest an air dryer needing replacement/complete service.  Put that on your short term "to do list".

My recommendation is a FACTORY (i.e. the factory that made it) reman. ...


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Re: We have a situation. Cycling air pressure
Reply #14
Tommy,

Suggest you e-mail Haldex and ask:

Are all connections on the new generation the same as your current one (provide model number of old one)?   Assume the reman unit IS.

What are the advantages of the new generation dryer?

Yes, inquiring minds...

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Re: We have a situation. Cycling air pressure
Reply #15
As Roger says, rough or winding roads use more air as the ride height valve levers move to add or dump air. I would also add that a properly adjusted ride height valve has a neutral or dead spot before the orifice lines up. In other words a very...

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Re: We have a situation. Cycling air pressure
Reply #16
The rear more than the front, every coach lean or suspension movement is a dump & fill operation, many times a normal situation.  Faster, bumpier, turning cause air loss. If driving slow on smother roads reduces the air loss everything may be normal.

Re: We have a situation. Cycling air pressure
Reply #17
Tommy,

Suggest you e-mail Haldex and ask:

Are all connections on the new generation the same as your current one (provide model number of old one)?  Assume the reman unit IS.

What are the advantages...


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Re: We have a situation. Cycling air pressure
Reply #18
Went out today to start to replace the air dryer. Raised the coach and attempted to place safety stands. I have the 12 inch harbor freight specials. All would go in except the left front. It was about 1/2 inch short. Tried a second time with same...

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Re: We have a situation. Cycling air pressure
Reply #19
That could have been your air leak at the beginning. Changing one air bag is not a good idea. If you are going to change all of them there is a thread about air bags less than $100 posted recently. If you are not going to change them yourself you...

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  • MAZ
  • [*][*][*][*][*]
Re: We have a situation. Cycling air pressure
Reply #20
John,
   I did my front airbags. The hardest one is the one by the steps. I had to remove the fender which is not that hard. Still was a slow process getting it out. The large nut is a lock nut so it takes a while to get it off. Here is a post...

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  • oldguy
  • [*][*][*][*][*]
Re: We have a situation. Cycling air pressure
Reply #21
I just finished changing my front air bags and with the right tools it's not bad. On my right front one I didn't remove the wheel and it
took twice as long as the left side. I didn't remove the fenders and I don't think it would of helped. I did...

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  • oldguy
  • [*][*][*][*][*]
Re: We have a situation. Cycling air pressure
Reply #22
Nice pictures Mark. I think pulling the wheel is easier but we are do things differently.

  • kb0zke
  • [*][*][*][*][*]
Re: We have a situation. Cycling air pressure
Reply #23
If you are thinking about replacing air bags seriously consider doing the shocks at the same time. If you are at a flat-rate shop, it won't make any difference, but if you are paying the the actual hours of work it will. We did the shocks a year...

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