Brake vent tube?

[jkelly66]

Is the air vent tube comming from my air pack suposed to blow a little brake fluid or do I have a serious problem? the master cylinder dosnt seem to be loosing enough fluid to matter.
Thanks in advance for all the help

 

[WillWagner]

No. Mine started as a small drip-drip-drip, then it turned into a stream every time the brakes were depressed. Maybe try a little air tool oil at the back side of the air pak, the seal in there might be dry.

 

[jkelly66]

thanks Will going to go try that now

 

[Recovry4x4]

Monitor your brake fluid before every trip. You never know when the problem will comppund itself. Although it may still be driveable, its not right.

 

[Katch1]

I thought mine would get better, but it didn't. But after I went through my brakes they work so well, it was well worth it. Definetly monitor the fluid, mine went from a little to a lot in a hurry

 

[jkelly66]

Ok thanks for the help thinking I might just go ahead and order a new one tomorrow

 

[WVSCOUTCAR]

Air pack in a duce

I bought the Air tool oil, but I cant find where to put it. The TM does not show where?
HELP!!!

 

[WVSCOUTCAR]

Air pack in a duce

I bought the Air tool oil, but I cant find where to put it. The TM does not show where?
HELP!!!

 

[WillWagner]

RE: Air pack in a duce

There is a "J" shaped tube comming from the front of the air pak/ masrer cyl, that goes to the back side of the air pak. there is a 1/4 inch pipe plug at the same end that "J" shaped tube goes into the air side. Make sure the air is bled off..there shouldn't be any threr unless the pedal is depressed, squirt some of the oil ino the hole..a couple of tablespoons worth.. re plug it, build air and work the brakes.

 

[moreorles2]

Master cyllinder question

Monitor your brake fluid before every trip. You never know when the problem will comppund itself. Although it may still be driveable, its not right.

Ken, I finally opened the floorboard inspection cover to take a look at the level in the master cyllinder. I was expecting to see a plug for quick access to view the fluid level. What I see is a plug that was tapped to accept what appears to me to be a return line from the airpack.
I find it hard to believe that one has to disconnect this line to view the fluid level as the wear and tear on the fitting would soon make this unserviceable after a few times at inspecting the level. Am I missing something here?

 

[doghead]

RE: Master cyllinder question

I find it hard to believe that one has to disconnect this line to view the fluid level as the wear and tear on the fitting would soon make this unserviceable after a few times at inspecting the level. Am I missing something here?

Nope! That's how mine are also. Almost makes you want to not check it often, huh?

 

[jasonjc]

RE: Master cyllinder question

Thats the army way

 

[rmgill]

RE: Master cyllinder question

Yeah. It's a pain. I recently filled mine to the brim (tricky to fill it cleanly) and then did work on the brakes and of course forced fluid into the breather line (that's what the line is) and that of course blasted fluid out onto the top of the air filter housing where it exits in the cab for the breather from the Air Pack and MAster Cylinder. It should be split from the fuel system's vent which runs to the road draft tube.

The vent is a pain to remove so you can get to the plug, but it can be done pretty quick once you get used to it. At some point, I'm going to re-run the vent to a container on the firewall that I can easily fill and monitor the level on. I'm not sure why they designed it that way though. Makes little sense.

 

[OPCOM]

RE: Master cyllinder question

If they had not put the darn thing under the cab crossmember, it would be simpler. After checking mine a few times, I though it might be simple to put a kind of fitting there that lets you slip a rubber hose over the fitting, and have the other end of the hose clamped to the vent tine. This might help since the vent line would not have to be bent each time the brake fluid was accessed. It's important to check the fluid. My brakes became somewhat weak, and I found that the master cylinder was almost empty. This happened over about 2 years, so it's probably not a real bad thing. Filling up the MC fixed it right up.

About running the vent to the higher container, is there any caution to be observed such as type of hose etc?

 

[Recovry4x4]

Might be advisable to run a remote reservoir up high on the firewall or in the cab. My old M108 had one mounted on the hardtop behind my left shoulder and a line running right into where the vent line goes.

 

[rmgill]

I'd figure that a properly run hardline would be easy to run from the normal location under the cab floor to the firewall. It's just a matter of finding the right type of vent line and tube and just a matter of adapting it all together. A polycarbonate container with a bottom hole would be ideal as you'd be able to see if it has fluid pretty quick. A vent off the top would be simple too in order to allow it to breathe as it should. You could even run that to the vent tube you run to a fording kit with an adaptor to keep it all high and dry.

 

[sermis]

I do not have a vent line on top of the master cap. It looks like someone put a petcock on top of the cap. There is a “T” fitting in the airline on the cross member. The “T” is open and has about 1” of pipe. Is this where the vent line goes to? It’s almost center of the truck.

Unless I am blind I only have one air pack booster. Is this normal or has someone modified the truck? Looking at the manual it should be duel circuit if I am reading it correctly. I used air to blow out the brake lines to the wheel cylinders and all seam to be on the same circuit.
The master is square with the brake line coming off the rear.

 

[littlebob]

I,ve seen the remote reservior idea come up before. should be able to do asearch and find it. If I remember correctly one member said he used a brke fluid reservior from the rear brake system on a motorcycle
littlebob

 

[cranetruck]

I do not have a vent line on top of the master cap. It looks like someone put a petcock on top of the cap. There is a “T” fitting in the airline on the cross member. The “T” is open and has about 1” of pipe. Is this where the vent line goes to? It’s almost center of the truck.

Yes.

 

[DDoyle]

90% of the 170,000 some thousand G-742 series trucks have only a single air/hydraulic cylinder. The op manual for these trucks is the TM9-2320-209-10. Only the very final trucks had the dual system.

All the elaborate venting is to allow deep water fording. I believe if fording and originality are unimportant to you, the vent line in the top of the master cylinder could be replaced with an axle breather.

HTH,
David