air escaping through air intake stack

has any one had this problem? preasure build up stops at 60psi then i can rev it up and go to 90psi and have brakes its losses psi, i sprayed the lines for leaks nothing even the compressor no hose leaks but when i trun it off it weeps threw the air stack so, the TM said to replace the quick realeas valve and parking brake valve, my problem is i have to get this M923A1 Tactor out of the GL yard in few days and dont have the parts does andy one know of a quick fix, like even take the lines off and spray some oil in the valves? or tapp them with a hammer if possible or any suggestions, it has new line on it but looks like old valve if any one has some new air valve parts for sale let me know.

thanks cal

Sounds like you have a bad diaphram in one of the brake chambers they exhaust the air into the intake so when it leaks thats where it ends up after airing up the truck shut it off and go around and listen to every brake chamber to find the leaker.You will have to cage the chamber by taking the T-bolt off the chamber it is stored in its own sleeve on the outside of the chamber Im not big on preaching about reading the TM but in this case you might want to read up on caging the brake chamber to keep from getting hurt or hurting someone else.

thanks bro ill have to try this, so i can drive down the road i wont have that one brake on that chamber then once its caged, i have caged a 5 ton back when i was in the army to tow so i know how to cage. the TM is like the bible some say but experice is where its at most of the time.

mahalo, cal

Newb question and slight thread hijack, so youre not supposed to hear anything through the air intake stack? When I release the emergency brake i hear like a squaking type noise. I have a 923a2, is thius normal?

ZEMMY, I have 2 werckers M936A1 and a M62A1, 2 tractors M52A1. this 932A1 that has the problem, 2 dropbed m923A1 yes the squaking in not happing with this one also when you turn off the motor you can hear a hissing coming from the air stack, ranchchopper said somhting that make sence i have go try what he said, have had my share of problems but this one is new and i need to get on the road and cant wait for the parts,so i need any advice that can work.

I think the air from the braking system does in fact exhaust into the intake its designed that way thats why there is so many air hoses on the 900 series trucks releasing the parking brake exhausts the used air from the brake chambers into the air intake.

If as above, the diaphram is leaking, and you cage the brake, yes you can drive with it, but you should stop the air leaking, as it can compromise your system. Several things are in my Kit to do that: An assortment of pipe plugs to stop off that line, but also an assortment of brake lining rivets. You can use one to block the air hose. Disconnet it at the chamber, insert it, and put the hose back on. It takes a sharp DOT cop to find that. It should be said that this is an emergency roadside fix, and not an approved repair, but it will keep you rolling.

Often, if a diaphram is leaking, the clamp can be tightened (if its the old kind, that clamps/be careful, go around the outside & tap the clamp, as you tighten it), but if its punctured, it needs replacement. Punctures are often caused by that "mean spring" in there breaking. All the stories about that spring are true. Its plenty mean, and use caution!

i too have this air sound coming from the intake once i shut off the 923a2. i will need to get in the tm section and find out what part i need to change on my brakes

I have a similar problem with my newly acquired M923. When I pressed the brake petal it dumps a lot of air into the intake stack. The 2ndary air pressure gauge drops pressure rapidly. We ended up turning off the shot off valve above the 2ndary air tank to stop the system from loosing a lot of air every time I depressed the brake pedal. With no air loss from the 2ndary tank the primary tank held air fine. Managed a safe trip home. Anyone know what is the problem or what to check?

I was told it could be a rip diaphragm in the spring break letting air into the stack. and hook up shop air to the glad hand to the service side then you can hear air passing through the leaky spring break if you have a hole in the diaphragm, I have to try this to see what one leaks, I replaced air dryer and treadle valve and a few in the box under the drivers door got all the parts for free all that did not fix it.

Try shutting the valve off above the tank that is behind the long tool box and see if it does the same thing it did on my truck.

I have not read all replies...

Sounds like a govenor gone south to me.

Grab a $20.00 Air Govenor and throw it in and see what happens...

Anyone have an answer as to where to check on my air system problem? Read above.

I agree with RH Mine does it and to my knowledge I don't have any issues. I drove it over an hour this weekend on country roads and had plenty of air pressure. I am fool over my gages and learned to scan them once every 5 minutes driving professionally. It sounds like may be more of a two part problem due to the fact that I hear the same thing some times but, don't have a loss of air pressure. I would check the obvious like open glad hands too. I hope you can find the problem Cal and have a safe trip home .......

did you find out about the air going into the stack? i hooked up shop air and same thing filled the tanks and cant hear no air going from the spring brakes on the rear, just hissing out of the 2hoses to the stack the TM Said replace some valves so i did and even chang the air dryer same thing some one had to have this same problem maybe its common?

Guys,guys,guys,cdl,cdl,cdl! If you have one,you know that an air pressure leak down test must be performed at the start of every trip. This test not only shows the importance of not driving a commercial vehicle with a faulty air system,it will also tell you which side of the system is the problem. Is the system losing air or not building air? Is the system losing air.with the brake peddle depressed? Simply charging the system through the glad hand will not find all possible problems. It was suggested by one to replace the air governor. Is the system not building air pressure? Once again,the leak down test will tell you this. There is no need to throw money at a problem trying to solve it. Mechanics call this the shotgun method. To find an air leak you first need to have a good understanding of how the system works and then have a helper to search the truck front to back,while the person in the cab operates the system. If you do not have good understanding of the system,then get a heavy truck mechanic to diagnose and repair. Using the shotgun method not only wastes money,but can give the false impression that the problem is fixed and ok to drive.
also,plugging an air line ahead of a brake chamber,is a method used by many truckers to stop the air leak at that chamber and allow the truck to be driven very slowly to the nearest repair facility. It is not legal and everyone should be aware,that if you were involved in any kind of accident,your fault or not,you would be in very deep do do.
lastly,I cannot over stress the importance of a cdl. These are not oversized pickups with automatics.they are heavy commercial vehicles that carry a tremendous amount of driver responsibility to safely operate them.

thanks for the advice its very well taken, i just drive my truck on my little farm dirt roads not on public roads.I wish i had cdl licence,i will have to study the air brake sytems and some day get one licence.

DD I understand the need for safety and I feel every one here knows when to call in a pro. This is a forum to reach out for help from people who have had issues with their M.V,s and look for peoples help and suggestions. I am a lifer in the transportation business with 25 years and over a million miles logged. I can appreciate your cdl and air break lecture but, I didn't ask for one and neither did anyone else, just advice on what problem could cause this situation to occur. I don't mean to come across in a condescending manner but, answers like your is why people don't post the questions to start with. So you DO have people using the shot gun approach instead of being given the proper advice and help with the problem They get a lecture and no answers to boot. Go easy and help your fellow SS members find solutions not insults ...........

Had the same problem with my latest M923. Ended up being 2 leaking diaphragms in the front wheels.

Is the spring brake diaphragm supposed to be field replaceable? Yes, I read the TM. It shows how to take the whole assembly off then just says " Check spring brake diaphragm for leaks". If there are details on replacing the spring brake diaphragm could you point the location in the TM for me? You just can't straight in present the can straight in to the housing. The pop off safety ears on the can requires that the can be twisted on wrinkling the diaphragm. I am going to try to lubricate the diaphragm with dish soap and/or lay hack saw blades flat on the diaphragm to slide the can over the diaphragm while twisting. BTW I am having trouble with the text editor. I can do CR's and after triple checking the text comes out all screwed up after publishing. I even compose in my word processor do a spell and grammar check cut and past and it still comes out screwed up.