Overnight Air Leakdown

Topic: Overnight Air Leakdown (Read 3227 times) previous topic - next topic

Overnight Air Leakdown

December 24, 2011, 02:06:43 pm

Hi all! Our coach has been sitting on frame blocks while I have been working on the subframe/bulkhead issues, with the leveling system off of course. Anyway, I noticed that the air pressure was down to about 15psi in both front and back, or low enough not to sound the air horn for my grandchildrens amusement:). So I started up the engine and let the pressure build up to cut off at about 9pm. At about 10am this morning, I looked and it was down to about 42 and 40psi respectively. In looking at the sticky about air leaks, I saw some had reported much less overnight air pressure loss. Just wondering where our coach is in the spectrum of being airtight. I figure that it is on my (long) list of projects to track down possible leak sources to make her more efficient as regards energy use and wear and tear on the 12v pump etc., I am hoping to use the results of the poll to prioritize my project list.
Regards, Don

Re: Overnight Air Leakdown

Reply #1 – December 24, 2011, 02:16:44 pm

Ours will be down to about 70 psi after a night, and then will drop slower, but after 4-5 days is down to 20 or so. I have occasionally done the soap solution testing, but haven't found any real major leaks.

Re: Overnight Air Leakdown

Reply #2 – December 24, 2011, 02:28:37 pm

Ours used to (two years ago) take more than 48 hours to bleed down. Now it is less than 24 hours. I have some investigating to do. Still far exceeds MVA leak down requirements of three psi/min, but .......

Re: Overnight Air Leakdown

Reply #3 – December 24, 2011, 02:35:05 pm

You can spend a lot of money tracking down minor air leaks with no functional benefit. Ask my how I know.

Re: Overnight Air Leakdown

Reply #4 – December 24, 2011, 03:09:00 pm

Mine will drop to about 90 over night, but will stayp on air bags for weeks and still be able to blow the horn to get the cats out of the garage,

Re: Overnight Air Leakdown

Reply #5 – December 24, 2011, 03:39:51 pm

"You can spend a lot of money tracking down minor air leaks with no functional benefit. Ask my how I know."
OK, how you know??

Did you find any leaks?

Been there done that, and still have the leaks to prove it

Re: Overnight Air Leakdown

Reply #6 – December 24, 2011, 03:58:24 pm

After accidentally finding and fixing the internal air dryer air leak ours will remain above #100 for several days. Once it drops to about #90 after a week it will set there for several weeks like Dave M's does.

Re: Overnight Air Leakdown

Reply #7 – December 24, 2011, 04:11:21 pm

Quote from: Pamela & Mike – December 24, 2011, 03:58:24 pm

After accidentally finding and fixing the internal air dryer air leak ours will remain above #100 for several days.

P&M - is this the post describing the leak? Remanufactured Haldex Air Dryer

Inquiring minds want to add their maintenance/service checklists

Michelle

Re: Overnight Air Leakdown

Reply #8 – December 24, 2011, 04:33:35 pm

Michelle,
Yes, that is the one. I looked around and couldn't find that post or I would have linked it in. (couldn't remember how it was titled) Thanks for the investigation work. We wish that we had taken pics. the last time we had it out as to help explain what we were talking about. (will be done next time)

Pamela

Re: Overnight Air Leakdown

Reply #9 – December 24, 2011, 07:01:08 pm

Just checked my air pressure after setting for one week, it dropped to 72 psi in a week.
We went over every fitting with the soapy spray, and found one slightly leaking fitting on the secondary air tank up front, also had the air operated vaccum pump replaced with the 12VDC pump, no idea if it were leaking, now if I could solve the Pressure Pro leaks that easy, would be a happy camper.

Re: Overnight Air Leakdown

Reply #10 – December 25, 2011, 09:05:12 am

After a few weeks my airbags will still be fine but the air tanks will show zero. It takes a while go get the last 40 psi to go but I have not had any issues.

Re: Overnight Air Leakdown

Reply #11 – December 25, 2011, 07:55:09 pm

I've spent more than $500 the past two years on FT resolving various small air leaks. Holding level has never been a problem. Now leakdown is much slower, but not $500 worth.

Re: Overnight Air Leakdown

Reply #12 – January 13, 2012, 08:31:09 am

Don,

We have been away from our RV about 30 days. We parked it on Dec. 15 and today is Jan 13. The air system was up to governor cut off at 120#. This A/M went down to the barn to check it over and the air was still at 45#. (The HWH was off so the 12vdc compressor wouldn't run if we had an air line failure while we were gone) We have never really looked at how much leakdown we have had over a months time and thought that this would give you a real time number. I feel that we have a pretty tight system with this small of leakdown.

Pamela and Mike

Re: Overnight Air Leakdown

Reply #13 – January 13, 2012, 01:08:42 pm

Thanks for the update, I would be happy with that number!
Don

Quote from: Pamela & Mike – January 13, 2012, 08:31:09 am

We have been away from our RV about 30 days. We parked it on Dec. 15 and today is Jan 13. The air system was up to governor cut off at 120#. This A/M went down to the barn to check it over and the air was still at 45#.

Re: Overnight Air Leakdown

Reply #14 – January 13, 2012, 02:17:47 pm

I am wondering what has been causing my rapid leakdown as do not hear any noises and think that the cylinders for steps may be culprit. How many of you have found these to be the source of loss of air?? I do not think I have a leaking line or surely I would hear it. I intend to build air up then remove pitons from step and let them retract and then soap them while step is not attached as I feel that maybe in the up position is when it leaks. Any ideas\

John

Re: Overnight Air Leakdown

Reply #15 – January 13, 2012, 02:23:33 pm

Sounds like an excellent plan! Please share what you learn from doing it...
Don

Quote from: John Haygarth – January 13, 2012, 02:17:47 pm

I am wondering what has been causing my rapid leakdown as do not hear any noises and think that the cylinders for steps may be culprit. How many of you have found these to be the source of loss of air?? I do not think I have a leaking line or surely I would hear it. I intend to build air up then remove pitons from step and let them retract and then soap them while step is not attached as I feel that maybe in the up position is when it leaks. Any ideas\
John

Re: Overnight Air Leakdown

Reply #16 – January 13, 2012, 02:35:26 pm

John,

Another air leak source is the piston on the entry sept cover when retracted so one can use the stairs.

Extend step cover, remove piston attachment, retract piston and soap it up to see any leaks around the piston seal.

Re: Overnight Air Leakdown

Reply #17 – January 13, 2012, 03:34:34 pm

There are just any number of places where one could have a small air leak. Federal regulations for air brakes on trucks seem to expect that and make allowances for small leaks. If it is specific to a certain spot like one corner of the suspension or front or rear that should help in tracking it down. My right rear air bags kept deflating overnight. The culprit was a solenoid valve in the rear six pack (six solenoid air valves mounted on an aluminum manifold). The manifold has a couple of exhaust ports, so one should apply soapy liquid there as well as air lines and connections. These solenoid valves either release or add air to the air bags. Two open for the travel mode and the other 4 control leveling when parked. In my case I was able to disassemble the valve, chuck the piston in lathe and turn the plastic seal smooth again, so that it sealed properly. Some pressure drop overnight is to be expected. A really tight system might hold air pressure for several days.

Re: Overnight Air Leakdown

Reply #18 – January 13, 2012, 05:31:56 pm

I had to change a step air cylinder for leaks some years ago. I had the key on for something and out side near the front of the wheel i could hear the leak. FT told me at the time that they wear in the step up position as we vibrate down the road.

Re: Overnight Air Leakdown

Reply #19 – January 13, 2012, 08:46:16 pm

my air bags stay fine for weeks but do suspect the step. I will check it out this weekend
John

Re: Overnight Air Leakdown

Reply #20 – January 16, 2012, 06:21:17 am

Mine leaks down overnight. There are a whole bunch for places for leaks as you are aware, all the little plastic air pressure regulators on mine are leaking at the front step, and front air manifold, ride height valves are leaking slightly in the travel mode key on, and on and on. It will sit on the bags with out leaking down, and the HWH keeps the coach level with out running the compressor very much if at all. In the end a bottle of soapy water and a bunch of time you can find them all. Mine is 13 years old air leaks are going to go on forever, like O/P's said you can spend a lot of time chasing leaks for no real benefit. 3 new ride height valves are next on the list as they will leave you stranded, and the air dryer could stand an overhaul. Ain't it a fun Hobby.

Aggravatin Air loss

Reply #21 – April 10, 2012, 09:59:46 am

When I got the coach out of storage after about 6 weeks, the level system was still up even tho I had the system OFF. I built air and then noticed that the step was slow to retract.
The next morning I found that the air had leaked off and I had zero air in the tanks and on the gauges.
I checked everything I could without getting under the coach with my back brace and found no leaks.
The next morning same thing, air gone. In addition I realized that I had not heard the air dryer popping off as air built up.
Y'day had a mechanic come over and crawl under and check for leaks all over. NO LEAKS, complete waste of time and money.
This morning air is holding at 100 PSI after setting overnite.
I can't explain it and now its got me worried. Intermittent defects freak me out, I would rather have a door fall off and know what it is than chasing down a minor squeak that you can never find.
No question here, just frustrated since we leave t'morrow for SC MC Rally.
Gary B

Re: Overnight Air Leakdown

Reply #22 – April 11, 2012, 06:31:19 am

Seems that engineers are not as fussy as owners. To accept any leak (my garage floor is as clean as the kitchen floor) from a vehicle seems silly to me. I remember something about "Leaks" and "Seeps" when dealing with airplanes: more than six drops a minute is a leaking fuel tank. Anyway:

I have been chasing air leaks for weeks now. (Ain't got much to do here at home until the ground warms enough for planting....) A surprising source for air leakage (soapy bubbles formed) was the small "regulator" valves coming off each front tank. These valves seemed to be constructed in two halves, with a rubber gasket sealing the matching halves. The simple fix was to tighten the four tiny screws holding the regulator together. On our 15 year old U270, this completely stopped one leak and greatly reduced the other leak on the pax side tank.

andy

Re: Overnight Air Leakdown

Reply #23 – April 15, 2012, 10:51:23 am

That regulator under the front is for the front air bag so the front comes up slower when raising coach. Mine was bad to and leaked badly. That was a large source for my air leaks. They don't make regulators like they use to. Art

Re: Overnight Air Leakdown

Reply #24 – April 15, 2012, 06:31:42 pm

I can sympathize with air leaks being hard to find. My right rear would leak down overnight. Searched for months, turned out to be the plastic seat on a solenoid piston/armature/plunger or whatever it is called. It was the exhaust solenoid for that side. Leak was so small it took several minutes to blow a soap bubble on the exhaust port. The solenoids can be disassembled. I was able to fix the leak by chucking the piston in a lathe and smoothing the plastic seat. Two weeks ago I parked the coach in the storage lot, raised it and put in the safety blocks, but didn't lower it onto the blocks. Turned off the HWH leveling system. Today the rear bags were still fully inflated, but the front bags had deflated a little. 40 psi still showing on both dash gage needles, but the air step had lost enough air that I could close it by hand. I'm happy with the fix. If you have an air leak, hope you can find it.

Affiliate Notice