What is this thing that's leaking?

['97International3800]

Can someone identify this brass contraption with hoses going into it? Is this part of the heater? It has air coming out of it, I can hear it softly hissing. The air doesn't smell like coolant, just smells like regular air actually. I think it blew a gasket or o-ring of some kind. It's on the driver's side against the firewall inside the engine compartment, near the top.

[Jolly Roger bus 223]

it looks like those or air lines to your systems
that looks like a diverter valve or distribution manifold.

[sportyrick]

looks like a master cylinder, is the pedal on the other side?

['97International3800]

Originally Posted by sportyrick

looks like a master cylinder, is the pedal on the other side?

Nope I've got air brakes.

['97International3800]

Originally Posted by Jolly Roger bus 223

it looks like those or air lines to your systems
that looks like a diverter valve or distribution manifold.

Is there an online parts fiche for Internationals or school buses that I can use to find a replacement gasket for this thing? I guess I can just make my own gasket out of cereal box cardboard and coat it with oil...

[sportyrick]

Ya'know call it what you want but it's the air brake actuator. Is the pedal on the other side? Gotta be, it's right above the steering column. If it's not an airline it's gonna have to get replaced, after all it's only your brakes. Mine is leaking also, it's only 45 years old.

[Jolly Roger bus 223]

you could call it a master cylinder?
it has the same style pushrod as a master cylinder but no booster or reservoir whether attached or remotes the tanks serve that purpose.
which gasket is leaking?
air brakes are high pressure systems so a DYI card board gasket isnt going to hold and if its leaking at the firewall then the( master cylinder) proportioning valve has probably failed internally. and needs rebuilt or replaced.

[CritiqueThisBus]

Originally Posted by '97International3800

Can someone identify this brass contraption with hoses going into it? Is this part of the heater? It has air coming out of it, I can hear it softly hissing. The air doesn't smell like coolant, just smells like regular air actually. I think it blew a gasket or o-ring of some kind. It's on the driver's side against the firewall inside the engine compartment, near the top.

That looks like....it will be expensive. Some sort of valve. Those do not look like fluid lines. An air metering/proportioning block?

If it is....hopefully it's just lines that have come loose over time and needs to be tightened up and/or have o-rings changed out.

[CritiqueThisBus]

Originally Posted by '97International3800

Can someone identify this brass contraption with hoses going into it? Is this part of the heater? It has air coming out of it, I can hear it softly hissing. The air doesn't smell like coolant, just smells like regular air actually. I think it blew a gasket or o-ring of some kind. It's on the driver's side against the firewall inside the engine compartment, near the top.

In your picture, the green lines say AIR BREAK on them. So it must be attached to the break pedal on the other side of the firewall. That would be something you want to get fixed pronto.

[LargeMargeInBaja]

Treadle valve.
.
It is engineered to vent if one (rarely both) distribution valve is tired and cranky.
Each axle has a distribution valve, usually mounted on a cross-member above the punkin.
.
In a quiet place:
Start the engine, build air until the purge whizzes.
Shut off the engine, walk around.
Listen for air leaks, particularly above the axles.
.
Alternatively, block the tires so the vehicle cannot move.
Start, build air until the purge.
Remove the key from the ignition, put it in your pocket, lock the entry, place a yuge placard on the door warning of your presence under the vehicle.
Crawl under the general vicinity of the cross-member above an axle.
Listen for leak(s).
!!! Eye-protection !!!
.
If I was me, I would replace the dist on each axle plus the master/treadle.
Figure about a hundred a piece (June, 2021 prices -- us$88 for each dist, us$126 for the treadle).
.
For brakes, I would try really hard to not go chinesium.

[rossvtaylor]

The green and orange/red lines are for your primary and secondary brake systems, so that's definitely part of the air braking system. Since you said it's near the top of the firewall, and not down where the pedal is, I don't think it's the treadle valve. It looks more like a proportioning valve to me, but unlike the Bendix ones I'm used to...so it may be something else. Just a thought, with the info we have so far.

[Rivetboy]

Another trick when chasing down air leaks is to use a piece of hose (garden hose, heater hose whatever) and hold one end to your ear and probe around your possible leak with the other end. This is handy in places where you cannot fit your ear to listen. Also, a squirt bottle with a little dish soap sprayed on will bubble. A strong light and rag with some solvent on it certainly helps when you are investigating, I like Purple and also Goof Off, certainly helps and occasionally, you can feel a loose connection.

Finally, this is your air brake system. The proper seals are MANDATORY.
If not used, you will be getting a text from Red Forman.

Most of us here know what that means...

[Terry jaye]

from the tag it is a meritor valve. Very carefully clean the tag and with the number you will be able to ID that valve. Sometimes the the contaminates will soften the lettering on the tag so use extreme caution

[Terry jaye]

the number is RKN31011 If the number is correct I believe it is a pressure protection valve

[Dirtdoctor]

Stop! AIR brake components are not to be MESSED WITH! Buy a new one and replace it. Fussing around with the most Important system for SAVING LIVES, is not to be done.
Learn about your Brake system! Those valves do wear out. Buy a NEW one. They aren't that expensive.
Cheers.
As a commercial driver we are REQUIRED to know the brake system, how to diagnose issues and adjust them. If you have airbrakes it would be best to know them backwards and forwards!

[cadillackid]

Originally Posted by Dirtdoctor

Stop! AIR brake components are not to be MESSED WITH! Buy a new one and replace it. Fussing around with the most Important system for SAVING LIVES, is not to be done.
Learn about your Brake system! Those valves do wear out. Buy a NEW one. They aren't that expensive.
Cheers.
As a commercial driver we are REQUIRED to know the brake system, how to diagnose issues and adjust them. If you have airbrakes it would be best to know them backwards and forwards!

and Buy GOOD parts.. aka DONT BUY DORMAN CRAP!
I generally buy Bendix and Haldex branded valves and parts for my Brakes...