Air leak on Brakes

[KaiserM109]

I know this has been talked about, I DID do a search and I was on one of the threads, but I have a slightly different question, so read on before you blast me.

On my M923A1 the left rear-most brake pack, for lack of the correct name, has a leak that is progressing fast. I work on the beast on weekends and only 4 weeks ago it was a very faint hiss, now it is louder and I have put less than 50 mi. on the truck in that time.

I know that there is a huge and deadly spring in the canister, BUT what if it is caged? Mine were all caged when I picked the truck up and I haven't uncaged them yet because I may still need to push it dead with my deuce.

This truck has what I am now calling "Kamikaze Maintenance", repairs that are only intended to last one more mission. It's driving me crazy!!

 

[Suprman]

So you are driving the truck with all the brakes caged? You are lucky to be able to stop with the service brakes they only work with pressure in the tanks. If you lost pressure you would have no brakes. If it were me I would have a professional fix it right. You are playing with fire.

 

[dilligaf13]

http://www.steelsoldiers.com/showthread.php?126598-M923a2-air-question&highlight=air+stack

This post covers your issue and also has diagrams, pictures, and part numbers.

 

[KaiserM109]

I have held off doing anything about the brakes, looking for a place that would do the work for me; no luck.

I found out today, the day before Thanksgiving, that my contract will end on next Friday, Nov. 5th. I did a Google search and guess what I found:

http://www.instructables.com/id/Replacing-Heavy-Truck-Spring-Brake-Diaphragms-read/

 

[Floridianson]

I'm doing the rears on mine now and they can be done without any problems. Just make shure the cage bolt locks in with a quarter turn. No need to take off any air lines. You wil need 8 # 12 and 4 #16 pancakes for the rears. I think every truck that comes to us should have all pancakes done as soon as you get the truck. I found mine at the local truck parts place and it cost me $ 40.00 for all eight rears and two front pancakes.

 

[wheelspinner]

I am going to blast you. The ONLY fail safe in that truck operating on a public road is the spring brakes. You need to uncage them, it takes 2-3 mins each. If you need to move it, sling an air hose from your deuce to the truck, it will air up just fine, or just recage them. With the brakes caged, yes you will have service brakes just fine, but you have no brakes AT ALL should your air supply suddenly fail.

And it is obvious to any DOT who looks (and if they get behind you, they WILL Look) that the brakes are caged.

Do yourself a favor, get this right.

 

[KaiserM109]

I am going to blast you. The ONLY fail safe in that truck operating on a public road is the spring brakes. You need to uncage them, it takes 2-3 mins each. If you need to move it, sling an air hose from your deuce to the truck, it will air up just fine, or just recage them. With the brakes caged, yes you will have service brakes just fine, but you have no brakes AT ALL should your air supply suddenly fail.

And it is obvious to any DOT who looks (and if they get behind you, they WILL Look) that the brakes are caged.

Do yourself a favor, get this right.

Your point is well taken.

I didn't know anything about it when I brought the truck home.

IT WILL NOT LEAVE THE STORAGE YARD UNTIL THE CAGING BOLTS ARE ON THE FLOOR OF THE TRUCK where I found two others.

Thank you for your concern and willingness to speak up. I think that this is something any new M939 owner needs to know about because I'll bet they cage a lot of them so that they can tow/push them around when they won't start.

 

[Coffey1]

Kaiser when you remove them they need to really go back in their storage on the cans not on the floor board you might need them again.

 

[porkysplace]

Your point is well taken.

I didn't know anything about it when I brought the truck home.

IT WILL NOT LEAVE THE STORAGE YARD UNTIL THE CAGING BOLTS ARE ON THE FLOOR OF THE TRUCK where I found two others.

Thank you for your concern and willingness to speak up. I think that this is something any new M939 owner needs to know about because I'll bet they cage a lot of them so that they can tow/push them around when they won't start.

It should have been easy to spot on your pre-trip inspection.

 

[Floridianson]

Ok have too take back what I said about easy and leaving the air line hooked to this unit. I started a new thread about the diaphragms and the unit that is on my truck.

 

[KaiserM109]

It should have been easy to spot on your pre-trip inspection.

YES, if you knew what you were looking at or for.

I would like to see a sticky created listing all the serious checklist items for each type of truck. I see a lot of newbies post 'what should I check for?'