Airbags Deflated? – Pump Them Up And Keep Them That Way!

August 31, 2012 chucker

Posted: 30 Aug 2012 04:10 PM PDT

Sad Right Air Bag – No Pressure

I like air bags. No, not the ones that save lives…though those are good too. The ones that help your suspension out and/or level your RV using nothing but air pressure. They’ve been around for a long time. It’s a mature technology that’s pretty reliable. Well, mostly. I’ve got a set of air bags on my real wheels. They help out the rear springs when the RV is loaded AND allow me to level the coach from side to side (and somewhat fore and aft.) The problem? A leak had developed on the right side air bag. We checked every inch of the air lines and fittings going from the bag to the dash valves and the pump/storage tank assembly. No luck. Turned out the “DOWN” valve for the right side airbag was leaking air into the gauge! You couldn’t hear it, you couldn’t see it from the valve. We finally found it by dousing (accidentally) the back of the gauge with soap bubbles from the spray bottle.

Bad “DOWN” Valve

The newer systems use electric solenoids to trigger valves to inflate or deflate the bags. Mine uses manual push valves. Four of them in two sets. Each set has an “UP” and a “DOWN” valve. I manually turn on the compressor to fill/refill the air storage tank, though I can set it up to automatically fill at a set pressure. To do it this way, you cannot simply use a pressure switch at the compressor (or storage tank) to feed power to the compressor so it will refill. The large amp draw will kill the pressure switch in short order. (Yup, I did it.) You HAVE to use a relay to switch the high amp draw item!! OK, to be fair you could find a pressure switch that would handle a high enough amp current to do the job, but it’s MUCH harder to find!

Typical air Bag System

The main problem with air systems is leaks. Anytime you put joints, disconnects, valves and fittings on any system it is a sure bet that a leak (or leaks!) will develop over time. Some of them are easy to find. Pump up your system and walk around listening for a HISS! of escaping air. You can also use the old fashioned “soapy water in a spray bottle” trick. Take an old (or new) spray bottle and mix some dish washing soap in it. Hold it upside-down and pump until some of the bubbles come out the nozzle then flip it over and gently spray onto anything you believe might be the leaky culprit. It makes it pretty easy to spot even slow leaks.

Air bag System Service Kits
Replacement Valves

Once you find the leak(s) then you have to fix them. If it’s a simple crack or hole in one of the lines, you can either replace the entire line or splice in a new piece using an inline connector. The connectors are pretty simple to install. Cut the line, slip it into the connector and press the plastic or metal ring down firmly. That locks the connector to the hose and prevents leaks. If your valves are leaking (like mine) or the gauge itself is dying a slow death, it can get a bit more complex. Depending on the vintage of your system, you may find that no one has ANY information about it or where to buy parts. In fact, you often cannot even get them to admit they built the kit in the first place! There are a couple of manufacturers that make small push button valves. I called both…..only one got back to me and they were VERY helpful. Even sent me a diagram of the replacement parts and how to use them. I would publish here, but the valves have a “mushroom” shaped button and the drawing was…well…a bit pornographic. Not on purpose….I’m sure! OK, maybe it was me and my wild imagination. *If you look closely at the photos, you’ll see the drawing peeking out from under the parts and plastic bags.*

Assembled Valve

The diagram was extremely helpful as the replacements connected a bit differently from the originals. I had to screw together various parts (all supplied) to build each specialized valve. The nice thing about these? They have little O-rings as extra seals at the base of each part. Once assembled I had ZERO leaks. Amazing.

Aggravating 90 Degree Bend!

Next up was crawling back under the dash to install the valves in the flat trim plate the gauge is mounted to. Thankfully, my dash actually lifts up and has prop rods that allow for decent access. Though you still have to be on your back, it’s not as bad as working on my car, upside-down on the seat! Once the new valves were connected up I found one small problem. Since the original valves both fed from the back, the normally straight shot for the tubing had to bend 90 degrees to go into the DOWN valve. Guess what? I was going to need about 2 inches of extra slack. That I didn’t have. I traced the line all the way to the “T” fitting in the engine bay and without replacing the ENTIRE line, I was out of luck. Since everything was already connected, I decided to fill the bags to 50 pounds and leave it alone for a few days to see if I lost any pressure.

50 Pounds And Holding!

After returning in a couple of days it was obvious that pressure was holding. In fact better than it EVER had! So, how do you fix the 90 degree bend problem WITHOUT replacing the whole line? I didn’t know it at the time, but after a quick call (and web site search) I found out that the same company manufactures 90 degree bend fittings for the tiny 10-32 threaded orifices on the sides of their valves. One with a swivel fitting, the other solid. Sent off a email and they were nice enough to send me both. Sometimes, things do just work out!

As soon as they arrive this week, I’ll put on the new bits and close up the dash, ready for my trip over the holiday weekend.

No more pressing the valve every fifteen minutes. Quite a boost to my already fragile sanity!

Be Seeing You…Down The Road,

Rich “The Wanderman