'89 345 rear air bags have no air

[DENNIS HAWS]

My compressor works, the tank has over 110 lbs. of air ,but the bags are not pumped up. there are no apparent leaks. I can not find the valve that lets the air into the bags. there are air valves on each side of the tag axle. the tank has 4 lines coming out of it that are very hard to trace. the lines connected to the air bags from the top are impossible to see and very difficult to get your hand in to feel. there is no actuator valve with an adjustable arm as i have seen in previous posts. can any one help?

[Smartstream]

Originally Posted by DENNIS HAWS

My compressor works, the tank has over 110 lbs. of air ,but the bags are not pumped up. there are no apparent leaks. I can not find the valve that lets the air into the bags. there are air valves on each side of the tag axle. the tank has 4 lines coming out of it that are very hard to trace. the lines connected to the air bags from the top are impossible to see and very difficult to get your hand in to feel. there is no actuator valve with an adjustable arm as i have seen in previous posts. can any one help?

Pictures would really help. There should be small arm/bar maybe 1/2" by 1/16" that come down and attach to the steel frame that the bottom of the air bag sits on. The valve will be at the top of the small arm/bar.

[bkahler]

The 345 with the tag axle will have two leveling valves. The valves themselves are mounted to the tag axle frame.

This diagram is from an 86 345 so I don't know for certain that it applies to your 89.



Try tracing each of the lines to see if they match the diagram.

Good luck!

Brad

[DENNIS HAWS]

First, thank you for your replies. The diagram looks exactly like my system (see attached pics) I still don't understand why neither airbag is getting air unless both valves have somehow stopped working. The tag axle is in the lowered position where it should be allowing air to get to them.

[DENNIS HAWS]

another pic - passenger side tag axle valve

[DENNIS HAWS]

another pic - passenger side tag axle valve

[bkahler]

Dennis,

The only thing that comes to mind is the Tee is plugged where it comes out of the tank and goes to each leveling valve. If the tank truly has air in it then I can't see any other possiblity. You should be able to manual move the valve lever arm to get it to request air. Be sure you're in no way in a position you could get pinched or trapped if it starts moving!

The only other possibility would be if the air gauge is stuck indicating air in the tank when there really isn't any. I believe the bottom of the tank should have a dump valve. Have you tried pulling that to see if air comes out?

Brad

[Smartstream]

Dennis disconnect this arm indicated by the arrow.



Now push the arm up and hold it. This will tell the valve to add air to the bag. Some valves have a 10 to 15 second delay so you have to hold it up for a bit. You should hear the air flow and see the bag begin to fill. Lowering the arm will release air. If you get no reaction you have to follow the air lines back to the tank and compressor to verify air in the system. There is also a check valve somewhere in the system. It is usually near the compressor in the output air line. It is a small fitting in the air line maybe 1 1/2" long with a hex on each end for a wrench. These valves tend to get plugged so remove it and clean or replace. The check valve is the only thing between the compressor and leveling valve that might restrict the air flow unless the line is kinked or pinched somewhere.

Good luck.

[bkahler]

Originally Posted by Smartstream

The check valve is the only thing between the compressor and leveling valve that might restrict the air flow unless the line is kinked or pinched somewhere.

Dan, I don't believe the above statement is correct. If you look at the plumbing diagram the compressor/fill side of the system is totally separate from the leveling valve side. There is a Tee in the tank that directly feeds the leveling valves. The compressor feed goes to a different port on the tank.

Based on Dennis's description either there is no air in the tank or the Tee feeding the leveling valves is plugged.

Brad

[Smartstream]

What I was saying Brad is that air lines and fittings don't contain anything to plug. The check valve has an internal moving part that can freeze up and stop the flow of air. If there is enough crud in the system to plug a tee or elbow then it has probably rendered the leveling valves inoperative a long time ago.

I personally have not had a problem with a check valve but reading Inland Andy's posts they fail on a regular basis and he sells many of them.

Dennis did state that he couldn't find a valve that lets air into the bags, that's why I suggested he remove the actuating arm and physically operate the valve to see if it's functioning. If there is air in the tank, there should be air at the valve. Also it's pretty easy to check without tearing into the system. Remember my lazy side, I like to check the easy things first.

[bkahler]

Originally Posted by Smartstream

What I was saying Brad is that air lines and fittings don't contain anything to plug. The check valve has an internal moving part that can freeze up and stop the flow of air. If there is enough crud in the system to plug a tee or elbow then it has probably rendered the leveling valves inoperative a long time ago.

Good point about the leveling valves most likely being plugged. Do you know if they can be taken apart and cleaned?

I personally have not had a problem with a check valve but reading Inland Andy's posts they fail on a regular basis and he sells many of them.

When we got our 310 the check valve was leaking (or was it missing, can't remembe now?!) and we got a replacement from Inland.

Brad

[Smartstream]

Originally Posted by bkahler

Good point about the leveling valves most likely being plugged. Do you know if they can be taken apart and cleaned?



When we got our 310 the check valve was leaking (or was it missing, can't remembe now?!) and we got a replacement from Inland.

Brad

Brad you are posting while I was editing, I guess I type too slow.

You used to be able to get rebuild kits for leveling valves years ago but like everything else the cost of labor made it cheaper to replace the whole valve.

If moving the actuating valve on the arm doesn't work the next step would be to loosen the inlet fitting on the valve to check for air pressure.

[bkahler]

Originally Posted by Smartstream

Brad you are posting while I was editing, I guess I type too slow.

I'm a speed typist...

You used to be able to get rebuild kits for leveling valves years ago but like everything else the cost of labor made it cheaper to replace the whole valve.

Sounds all to familiar

Brad

[DENNIS HAWS]

The way I determined the tank pressure was with a tire guage on the tank drain\schrader valve. If I let out all of the air, the compressor comes on and pumps it back up to110. I tried moving the valve arms but they won't move up further unless I take off the nuts which should be high enough anyway. The other way it seems like I'm putting too much pressure on them to get them to move. This may be a clue. These valves must be the initial source of air as per the diagram so I'm going to start cracking the fittings loose and tracing the air. I also am going to remove the nuts on the control arms to see if I can get them to move up further.

[Smartstream]

Originally Posted by DENNIS HAWS

The way I determined the tank pressure was with a tire guage on the tank drain\schrader valve. If I let out all of the air, the compressor comes on and pumps it back up to110. I tried moving the valve arms but they won't move up further unless I take off the nuts which should be high enough anyway. The other way it seems like I'm putting too much pressure on them to get them to move. This may be a clue. These valves must be the initial source of air as per the diagram so I'm going to start cracking the fittings loose and tracing the air. I also am going to remove the nuts on the control arms to see if I can get them to move up further.

Dennis just pull that hairpin clip and slide that actuating arm off the threaded adjusting rod. The weight of that arm is enough to open and close the valve. There should be virtually no resistance at all to move that valve arm up and down, maybe just a couple of ounces of pressure to operate the valve. Remember there may be a delay in the valve so once you raise the valve arm you might have to hold it for minute before you get air flow.

[DENNIS HAWS]

I did that very thing on the curbside valve. The arm was easy to move up, and when I did the bags filled up. yeah! I then tried the street side one. It only seemed to work to let air out. The bags are up now so tomorrow I am going to test drive it a little. I will give you an update afterwards.
Thanks, Dennis

[bkahler]

Dennis,

From your description it sounds like one valve filled both air bags. I was under the impression that each valve handled one air bag.

Can't wait to hear the results of your test drive!

Brad

[DENNIS HAWS]

The test ride went great. The bags are up and it rides real good. My next step will be to let all of the air out of the bags , and then see if the opposite side valve will air them up. When I tried it before the bags possibly were all of the way up. I will let you know what happens.

Dennis

[bkahler]

Originally Posted by DENNIS HAWS

The test ride went great. The bags are up and it rides real good. My next step will be to let all of the air out of the bags , and then see if the opposite side valve will air them up. When I tried it before the bags possibly were all of the way up. I will let you know what happens.

Dennis

Dennis,

I stand corrected. I just looked at the air diagram again and it looks like either valve can add or remove air from the air bags. The leveling valves are located on the tag axle so I'm guessing that if a valve senses that one side is low it adds air to force the whole back end up. It doesn't correct for lean side to side which is what I though the separate valves were for.

Glad to hear your test drive went well. Sounds like you're on the right track!

Brad

[DENNIS HAWS]

The other valve will not air up the bags, but it should. I loosened both lines at the valve and no air came out. I ran out of time, but will be back at it soon. I will keep you posted until the problem is solved.

thanks for your support!

Dennis