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Top Air Gauge Dropping

We've been parked on a level site for nearly a week. For the first time in 3 months on the road I noticed the top air guage has dropped.  Prior to this time both gauges would slowly drop over a week or so from 110-115 to 90-100 or so.  We moved the coach slightly on our site yesterday and I noted a shutdown pressure of 110-115 on both tanks. This morning the top guage shows 70 and the bottom guage is still 110.  I'll watch today to see if the top guage falls further.

We'll be covering roughly 1200 miles over the next 2 weeks and generally located away from major Service centers.  How significant to travel safety is this issue?  Both tanks quickly came up to travel height when we moved yesterday.

Thanks

Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Top Air Gauge Dropping

Reply #1 –
Quote from: floridarandy –
  How significant to travel safety is this issue?

Not at all.

You could have a check valve leaking on the line that feeds the air tank or a slight hose leak at a fitting.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Top Air Gauge Dropping

Reply #2 –
Turn everything off and listen around the park brake valve  for a faint hiss.  The acceptable leak down is well above your values.

Re: Top Air Gauge Dropping

Reply #3 –
Over 150K miles my air system has never been that tight.  Go!!
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Top Air Gauge Dropping

Reply #4 –
Since posting the top guage has mirrored the bottom and both have resumed their "normal" and acceptable leakdown. What would cause this to happen sporadically?  Not concerned at this point.
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Top Air Gauge Dropping

Reply #5 –
Quote from: floridarandy –
What would cause this to happen sporadically?
Intermittent malfunction of gauge (if mechanical) or of sender/wiring/grounds (if electronic).
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Top Air Gauge Dropping

Reply #6 –
I had to replace one of my gauges when I experienced the same condition. if it does it again switch the air lines on the top with bottom gauge, and see what it reads,
John
1998 U270 34'
 

Re: Top Air Gauge Dropping

Reply #7 –
Quote from: floridarandy –
We've been parked on a level site for nearly a week. For the first time in 3 months on the road I noticed the top air guage has dropped.  Prior to this time both gauges would slowly drop over a week or so from 110-115 to 90-100 or so.  We moved the coach slightly on our site yesterday and I noted a shutdown pressure of 110-115 on both tanks. This morning the top guage shows 70 and the bottom guage is still 110.  I'll watch today to see if the top guage falls further.................How significant to travel safety is this issue? ..........................
Randy,
You have a good, leak tight system.  Don't be concerned.  Just stay aware of trends.

You need to realize that when you move a coach from one position to another, no matter how small or how undramatic the changes may seem to be in terms of leveling system actions, literally dozens of valve to seating surface conditions were changed during the short moving process.  Compressor to D2 governor to check valves on tanks to six-packs to leveling valves — a lot of seating surfaces have been exercised, even in a short repositioning event.  If any one of those valve to valve-seat changes ended up not quite perfectly seated, for instance due to a temperature or a contaminant particle influence, there may well be nothing unusual about your occurrence.  There is also a very high probability that the anomaly will clear during the next exercise of the coach.

You need to sit up and take notice when you notice major, repeatable degradation step changes, toward FT and then DOT air leak specifications. The air leak specs are nicely summarized in BeamAlarm:

D.O.T. Standard Allowable Leakdown

Easy summary:

FT = 6 psig drop/hour = 60 psig drop/overnight
DOT = 4 psig drop/2 minutes

HTH,
Neal
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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten