I have the air bag system listed in my sig below. Somewhere there is a leak. After spending over an hour with the soapy water and brush routine under there finding nothing, I gave up and just put a little air in them whenever I use the truck. My question is, why do the bags have to have air in them when running the truck? The owners manual says to never run them empty. I haven't tried this, but if I forget to top up on day, what can it hurt?

 

no air could mean that you will pinch the bag and cause a leak in the bag itself.

Did you check for a leak at your guages? I have a small one on the drivers side inlet to the guage...every couple of days I need to add a little. I will wait for warmer weather to fit it though.

 

I only have a remote electronic digital gauge in the cab so no possibility of a leak there. Thanks for the info on the bags. I usually just keep 7-10 lbs when unloaded so I don't imagine they could pinch any easier there than completely empty. It's just annoying to see the digital readout flashing because the pressure is too low...

 

Your digital gauge must have a sender that connects to the air system. Have you checked there?

In big truck air bag systems, the leak is most often at the bag itself. The reason is that there is hardly anything else in the system that moves. Motion introduces the chance of a leak. Most leaks in air bags are caused by rubbing against adjoining structure. Some leaks come from fatigue from the constant flexing of the bag.

If you have enough access, it is very effective to use a small spray bottle (like a plant sprayer bottle) and mix dish soap in it. Use it to spray the area to be tested. Charge the system to the maximum recommended pressure to make the leak as active as possible.

 

Q. Do I have to keep air in the springs all the time, and how much pressure do I need?

A. Yes, always maintain the recommended minimum air pressure, even when unloaded. This keeps the air springs “in shape” so they move through their normal travel without rubbing or wearing. Minimum air requirements vary with vehicle and load; your instruction manual will give you the recommendations for your vehicle

 

Yes, I have a sending unit. Yes I checked there. Nothing. Maybe the onboard compressor is leaking. Not sure, but it's not leaking at the connection. I did check the bags with soap and water. Nothing. The minimum is 5 lbs which I always add to it whenever I head out. Funny thing is, the leak has varied since I put the system in last spring. It would always loose a few lbs a day since new. Then I aired way up to 80 lbs for a very heavy trip. Left it like that for the weekend. When I got home it held air perfectly at any pressure for weeks. I figured I seated all the connections with the higher pressure and was very happy. Then this fall out of no where it started really loosing pressure. While hauling my TT home from a trip it would loose 5-10 lbs an hour. Now it looses it's pressure over night every time. I have tried airing way up and leaving it that way to see if it would seal things up like it did this spring but no luck. Also crazy is that it seems with a leak this big it would be easy to find. NOT. Now it's too cold to play with so I guess I will wait til the spring and pull both bags and inflate them in a pail of water to see if I can find it. Really at a loss here. I wish these things were more reliable. I spent over 600 for the set up and it's failed since day one. I would not buy it again.

 

do you have the shrader valves installed ? check those well or cap them if they don't have valve stem caps on them
mine looses air also and I had a heck of a time finding it ( never did ) but my new remote control and compressor automatically holds a minimum pressure or any pressure I select so it just bumps air into it every so often ,,

 

What Zmann said... I would start by replacing the schraeder valve and use new metal caps with fresh seals in them. If that didn't fix itg, I would remove, trim, and re-insert the air lines into their fittings.

For the record, I've installed 5 systems with absolutely no leaks, so yours is an unusual case. Once you find and fix it, you will like them.

 

i have the Firestone system in my truck and i tend to keep from 20 to 30 PSI depending on temp. with the truck empty..

i havent noticed any leaks over time other then with swings in temp.

sorry man, maybe just run a higher PSI all the time and see how it goes.

 

I don't have the schraeder valve's installed as I only use the onboard compressor. Will be pulling the lines, re cutting, and trying again in the spring. Strange thing is I can't find the leak with the soapy water solution at any of the connections. Also, have tried leaving higher pressure in the system. Just leaks faster...

 

That's when you need to try the soapy water. Higher pressure with faster leaks will be easier to find than an extremely slow leak. Air it up to 100 psi and get out the spray bottle.

 

You can eliminate the compressor as a leak by disconnecting the line to the compressor, installing a schrader valve to the line, the pressurizing the system using the schrader valve to 80-100 psi. Use your soapy water to make sure the valve and fitting isn't leaking. If the system still leaks down at the same rate, you have eliminated the compressor as a leak.

If you only checked the fittings and joints with your soapy water, then the leak is either in an air bag or one of the lines between the fittings.

 

Try this:

Disconnect the hose at the pump control in the cab
Apply compressed air to the end of the hose with a blow gun
Have a helper listen for and look for leaks with the previously described soap solution
I'd bet on a fitting leaking

 

I have had the Firestone bags installed since 2008 and never had any problems at all. You just have a leak somewhere, it's not the quality of the product. Just a frustrating problem for you to solve.

Did you check the bottom of the airbag where the bolt goes in to secure the bottom to the bracket? Seems like a difficult spot to check to me. Would be easy to just unbolt it, renew the seal with some teflon tape and try again.

 

Well, despite what everyone thought, it was a quality control issue and not a leak in the system. I doubted my own eyes after reading everyone's posts and figured I must have missed a leak even tough I went over all the lines and fittings more than once with soapy water. Funny thing happened though. This winter, a few times, it held air for 4-6 days. Got me to thinking. If there is a leak, there is ALWAYS a leak. It can't stop and start. So, I thought, what is the only variable in the whole system? Since I have no air tank the compressor holds the pressure and must have a one way valve. I figured the leak must be in this internal valve. I called Firestone tech who thought my theory sounded plausible and sent me a new compressor. Well, I am proud to say, for once I was right in a diagnoses! Rarely happens so I'm pretty impressed with myself. Anyways, just wanted to give closure to the issue if anyone was interested.