Community Forums

bpu699 · 07-26-2022, 06:22 AM

True of false...

If your front suspension airbags settle overnight, then your front air levelers valves MUST be leaking?

Meaning: If your air levelers didn't leak at all, then the airbags would always be permanently inflated, even if there were other leaks down the line...

MY rear suspension will stay up for a year without use. The fronts go flat within 48 hours...

I cant find any leaks, and trying to logically think through this...

Bruce Anthon · 07-26-2022, 06:51 AM

Any connection between the leveling valve and the air bag plus the air bag itself can be a source of lost air. Kid’s bubble soap sprayed over the connections, hoses and bags will show the problem quickly. It has been my experience it is rarely the valve it’s self (but could be). The attached photo shows an overnight air leak that could not be heard. It ended up being two brass fittings that just needed to be tightened.

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bpu699 · 07-26-2022, 06:56 AM

I've sprayed everything with soapy water, and even bought a sonic air leak detector... no noted leaks found. Yet, front airbags still go flat.

I guess my question is really a plumbing question...

Bruce Anthon · 07-26-2022, 07:08 AM

I understand your frustration. But just soapy water may not show it. The bubble mix is sprayed on undiluted. It took about a minute of waiting before the first bubble appeared. Because the solution is so clingy, the bubbles continued to build. That photo is about 10 minutes after it was sprayed.

You explained that the rear holds and the front drops. What does your air gauge show over night? Does it stay up as well?

bpu699 · 07-26-2022, 07:40 AM

Front and rear air gauges fall simultaneously down to 60 psi over 2 days. Then linger there for weeks slowly going down. After a couple months its at 15 psi.

Rear suspension NEVER goes flat, which makes me believe the air valves are the culprit in the front.

Argosy · 07-26-2022, 08:15 AM

It could be the air bags, did you check them?

bpu699 · 07-26-2022, 09:14 AM

Quote:

Originally Posted by Argosy

It could be the air bags, did you check them?

Sprayed them, no visible leaks.

Is my presumption correct, that it HAS TO be the airbags or air leveling valve?

Gary RVRoamer · 07-26-2022, 11:50 AM

Any of the plumbing from the air leveling valve to the air bags themselves. You didn't mention a coach year/make/model or a chassis, so not sure what plumbing yours has.

DRM901 · 07-27-2022, 09:39 AM

Quick connect fittings are prone to failing. If you have any between the tank and the bags, I would look at them carefully. I've used the plumbers leak detect solution. It's thicker, clings better, and shows bubbles a little better. Pretty cheap too at Home Depot/Lowes.

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bpu699 · 07-27-2022, 09:43 AM

Quote:

Originally Posted by Gary RVRoamer

Any of the plumbing from the air leveling valve to the air bags themselves. You didn't mention a coach year/make/model or a chassis, so not sure what plumbing yours has.

2000 Winnebago ultimate advantage…

Keep thinking this info shows up under my avatar

mackwrench · 07-27-2022, 06:21 PM

Not sure what leveling valve you have but some have a short piece of nylon line that's plumbed in the exhaust port, usually about 4 or 6 inches long. Be sure you spray it as well, the valve could be leaking internally out of the exhaust.

Does your coach have one or two leveling valves on the front axle? If two, and both sides are leaking down, then I'd suspect the dump valve is your issue.

.....to answer your question in theory the suspension should stay "aired up" even with no air psi in tanks....

RichardE · 07-27-2022, 08:18 PM

The leveling solenoid may be leaking, but do yourself a favor and run a quick, cheap, and effective experiment before you buy new valves.

Crib or support the coach before you do any work under.

Disconnect the lines from the leveling solenoid block that feed the air bags. Insert a quarter turn shutoff valve in each line and reattach to the leveling block. Inflate the front. Turn the valves to the shut position.

If the coach still settles, then the leak is NOT in the leveling block or valves. If it doesn’t settle, then your idea about leaking valves is worth pursuing.

Skip426 · 07-27-2022, 10:26 PM

I'm assuming Spartan chassis , as in this 01 pdf .

There is a PPV ( Pressure Protection Valve 60 psi ) at the #2 air tank . there should also be an isolation valve between tanks one and two .
If your air suspension is leaking only tank two should go down and stop at 60 psi , tank one should hold the pressure it had at engine shut down for days .

The diagram shows the Spartan air suspension system uses a tank dedicated to the rear suspension ; which explains why the rear stays up ; but doesn't show any isolation valves between front and rear suspension , that would keep a leak up front from draining the pressure from the rear.
Your system includes the air bags , ride height valves , (air dump solenoids ?) and all the interconnecting lines. But an overnight leak down shouldn't be too difficult to find, but it will take time and determination.

bpu699 · 07-28-2022, 05:40 AM

Quote:

Originally Posted by mackwrench

Not sure what leveling valve you have but some have a short piece of nylon line that's plumbed in the exhaust port, usually about 4 or 6 inches long. Be sure you spray it as well, the valve could be leaking internally out of the exhaust.

Does your coach have one or two leveling valves on the front axle? If two, and both sides are leaking down, then I'd suspect the dump valve is your issue.

.....to answer your question in theory the suspension should stay "aired up" even with no air psi in tanks....

Both sides leak down equally. There are 2 leveling valves, one on each side. If it were the dump valve, wouldn’t all 4 corners go down?