Air Brakes

[3up]

One more thing is when its building up the air you hear a big release like a big diaphragm and then about three or four minutes later another one and the owner that had it said it's ready to go after the second fart

 

[3up]

Im going to replace the PPV and any other valves that may need it. Im still learning how the whole system works. Thank you guys for pointing me in the right Direction, I have not seen another like this truck it is not cammo the box has smooth sides (no lines) 80gal tank on both sides and hardtop looks like it's been there for 30 years.

 

[3up]

The tires look 10 years old lite checking see pic, In your experience where they good to go with that type of checking or do they disintegrate as soon as you start driving it again

 

[Floridianson]

Getting old CRS but is not the air dryer around there too. OK if our governor was allowing 150 then the pop off valve might just be popping off. Truck air if I remember 120 psi. If it is pop off and you have 120 then maybe service the over pressure valve .
Truck looks good and a good gust of wind you will feel it with those big sides. Will drink some fuel so I will invest in some fuel stocks for when you start driving it.
What fuel station do you use most and that company is the one I will invest in? Yes I have owned a couple of them. Cool trucks even took off the box on one of them and made a ground shop powered up.
Believe here is a thread about the pressure protection valve that holds air in the main tank incase of problems. Do a search in 5 tons type in pressure protection valve and there are plenty of threads. Technically the one screwed into any tank on the side and no lines in or out is an over pressure protection valve or pop off valve. Brakes? 15 miles from home - M923A2 | Page 2 | SteelSoldiers

 

[3up]

Getting old CRS but is not the air dryer around there too. OK if our governor was allowing 150 then the PPV might just be popping off. Truck air if I remember 120 psi. If it is PPV and you have 120 then maybe service PPV .
Truck looks good and a good gust of wind you will feel it with those big sides. Will drink some fuel so I will invest in some fuel stocks for when you start driving it.
What fuel station do you use most and that company is the one I will invest in?

Dryer is on that side, yes its big but i dont drive far maybe 300 mi a month. Fuel is going to be my new rent

 

[98G]

A brief overview of the air system-

Truck starts. Has no air. Begins building air.

Pressure rises. When it hits 70psi or so, the PPV opens and "nonessential" equipment gets air. This includes wipers, horn, tcase, and air governor.

At 120psi the expello valve on the air dryer sneezes, and air is sent from the governor to the unloader valve on top of the air compressor. Air pressure stops building.

The above is what happens when things are working normally.

If the PPV doesn't open (a very common problem) , then none of the nonessential equipment gets air, the governor never sees air, and the unloader valve on the air compressor never gets the signal to stop building air.

Pressure continues to rise. To prevent catastrophic overpressure failure, there's a pressure relief valve that pops at 150psi. It'll cycle every few seconds, and sounds something like a very angry air dryer expello valve.

To people with a background in commercial air brake systems, this seems like an air governor problem. It isn't. They replace a perfectly good governor, and the problem doesn't go away.

As mentioned above, the PPV can be cleaned and serviced and likely restored to service. Replacing is easier and faster and more certain, especially for someone who hasn't worked on this stuff before.

The root cause of almost all air related problems on these trucks is moisture in the system.

 

[3up]

A brief overview of the air system-

Truck starts. Has no air. Begins building air.

Pressure rises. When it hits 70psi or so, the PPV opens and "nonessential" equipment gets air. This includes wipers, horn, tcase, and air governor.

At 120psi the expello valve on the air dryer sneezes, and air is sent from the governor to the unloader valve on top of the air compressor. Air pressure stops building.

The above is what happens when things are working normally.

If the PPV doesn't open (a very common problem) , then none of the nonessential equipment gets air, the governor never sees air, and the unloader valve on the air compressor never gets the signal to stop building air.

Pressure continues to rise. To prevent catastrophic overpressure failure, there's a pressure relief valve that pops at 150psi. It'll cycle every few seconds, and sounds something like a very angry air dryer expello valve.

To people with a background in commercial air brake systems, this seems like an air governor problem. It isn't. They replace a perfectly good governor, and the problem doesn't go away.

As mentioned above, the PPV can be cleaned and serviced and likely restored to service. Replacing is easier and faster and more certain, especially for someone who hasn't worked on this stuff before.

The root cause of almost all air related problems on these trucks is moisture in the system.

Thank yiu for that i pasted it in my phone so i can memorize it where does everyone buy valves and stuff like that from ? I will replace the PPV valve and see what happens after that how often should you drain the air out of those tanks? And a new air dryer will help the whole system it sounds like.

 

[Crf450x]

If it only makes 120 psi, not 150+, the ppv is fine.....

Maybe make a video of what you're talking about. Sounds to me like you just have a leak causing it to cycle excessively.

 

[3up]

If it only makes 120 psi, not 150+, the ppv is fine.....

Maybe make a video of what you're talking about. Sounds to me like you just have a leak causing it to cycle excessively.

Yes but only cycles driving. Sounds like when a semi passes maybe there air shifter. Its not a big diaphragm noise i will drive it and have someone record it. Is there a limit to how many pics you can post here?

 

[98G]

If it only makes 120 psi, not 150+, the ppv is fine.....

Maybe make a video of what you're talking about. Sounds to me like you just have a leak causing it to cycle excessively.

Agree.

Also, if you have horn, wipers, or tcase air then it also isn't the PPV.

 

[Floridianson]

Agree.

Also, if you have horn, wipers, or tcase air then it also isn't the PPV.

Agreed and the PPV does not pop off with air it just does not open main problem. I after reading post and he said it pops off air should have corrected usage of PPV and not used PPV term like he did. Air dryer pops off and pressure relief pops off.

 

[Floridianson]

If it only makes 120 psi, not 150+, the ppv is fine.....

Maybe make a video of what you're talking about. Sounds to me like you just have a leak causing it to cycle excessively.

Here to it is pop off not PPV term. Guess I started it and should have corrected him right away. My bad. A leak would not cause to pop off every 6 seconds. Sometimes the lower unit on the air dryer gums up and will not close right. Sometimes you can take something small and round and blunt push up through the bottom of at purge valve and get it to stop if it is stuck open for awhile but the air dryer needs to be serviced. That or the pop off ( pressure relief ) set to low can pop off . When I said service the unit I was thinking pop off. This is what happens when you get old and grumpy. Can not chew gum and think at the same time or think and type.

 

[Floridianson]

 

[Mullaney]

Yes but only cycles driving. Sounds like when a semi passes maybe there air shifter. Its not a big diaphragm noise i will drive it and have someone record it. Is there a limit to how many pics you can post here?

.
You asked about how many pictures... I believe there is a limit of 10 per post and you can post pictures until you get tired.

About the air problem... Do you by chance happen to have "house air" at your house / shop? Or an air compressor just sitting there in the garage waiting to air up a tire? If you do, connecting your compressor to the truck will let you air up the truck without all the noise generated by the truck running. If you have a compressor - let us know and we can help you connect it to the truck...

This is more to search for leaks than anything else.

 

[Crf450x]

A leak would not cause to pop off every 6 seconds.

This is true…I had 3 or 4 minutes in my head from the post above. I’m interested to hear it.

 

[3up]

I’d definitely do a little diagnosing before firing up the parts cannon…and even if it is the ppv, you can take it apart and fix it for next to nothing rather than buying a new one. That’s just my opinion.

Parts cannon that's hilarious. My younger me definitely use that a lot

 

[3up]

I do have an air compressor that i can hook up to it

 

[Mullaney]

I do have an air compressor that i can hook up to it

.
You have the M934, so you have "real" air brakes. Applying air to the left (drivers) side gladhand will release the parking brakes.

1. Park on flat ground and CHOCK YOUR WHEELS just to be safe.
2. Check your "house" air compressor pressure. 120#, and no more than 150#
3. Get yourself a gladhand. Relatively inexpensive. Mate that up to your air compresser hose.
   - I would suggest a quick connector like on an air chuck in the gladhand.
   - Affix the glad hand to the gladhand on the drivers side, then attach the house air.
4. Fire up the compressor and wait. You will air up the trucks air system.

If there are leaks on the truck anywhere, you should hear them. Joy or Dawn in a spray bottle on anything "making an air noise" will get you to a way prove where the leak is.

Don't hesitate to ask questions.

This testing described above WILL NOT solve an air dryer problem if you have one. The air dryer receives the air from the truck air compressor. If you have the factory dryer, it has a bag of desiccant in a bag inside the bottom of it. There is what I call a spit valve on the very bottom of that dryer. Most of the time it either works or bleeds air all the time. There is nothing inside the dryer that cause it to "spit" other than pressure.



It might be worth your time to open the dryer and see if it is nasty - or clean. Many of the guys have purchased a new Haldex replacement for this part. Part number is in the 5-Ton Parts List & Filter Numbers spreadsheet (Line 12. Again, rapidly puffing air isn't going to be solved by replacing this part. Remember the Parts Cannon.

If you can get the possibilities of leaks out of your system - and if your dryer really is drying the air that comes out of the compressor - we can look at the next step to solving the problem. Lots of the guys have made really good suggestions. Mine are down in the very basics of the air system, but everything they are suggesting is built on top of a no leak air system.

 

[3up]

Ok i will get on that tomorrow, this parts list for the 5 ton is where exactly??

 

[Mullaney]

Ok i will get on that tomorrow, this parts list for the 5 ton is where exactly??

5 ton Parts Quick Reference Spreadsheet

Ok guys, here is a spreadsheet I have worked up just to assist people on locating some parts on short notice via local stores as well as some others. If you have any parts you want to add send me a PM with the part number and who supplies it. This is just a test sheet for now. I am still...

www.steelsoldiers.com