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Topic: Building Air Pressure (Read 1180 times) previous topic - next topic

Building Air Pressure

Traveling west in lower temps and higher elevations. Each morning air pressure is at 30 psi. It's taking me 1.5 to 2 hours to charge with higher idle. I have an appointment at MOt to check governor and leaks. In the meantime, could I use my pancake compressor to charge the air tanks using the aux air compressor port in the engine?

Re: Building Air Pressure

Reply #1 –
Assuming you hear no large leaks (check this FIRST), just replace the air governor.  Under $25 and the same as on any OTR truck.  EASY.

It may not be the problem, but replacement is less $$ than even paying someone to come out and look at it.

Re: Building Air Pressure

Reply #2 –
Quote from: Greg & Erin Burress –
Each morning air pressure is at 30 psi. It's taking me 1.5 to 2 hours to charge with higher idle.

Greg,

If it takes this long to build air pressure you sure need to see about finding the problem. Does the compressor get to full pressure on your dash gauge?  Taking this long to build air could be a problem with your brakes if you are loosing that much air and not recovering like you state. Check the compressor discharge line for leaks,  Look close at your air dryer to see if it is purging all the time out the drain.  It could have a broken/stuck unloader or valve in the compressor which is unlikely but possible.

Mike

Re: Building Air Pressure

Reply #3 –
Quote from: Greg & Erin Burress –
Traveling west in lower temps and higher elevations. Each morning air pressure is at 30 psi. It's taking me 1.5 to 2 hours to charge with higher idle. I have an appointment at MOt to check governor and leaks. In the meantime, could I use my pancake compressor to charge the air tanks using the aux air compressor port in the engine?
When you shut down with full pressure, how fast does the pressure drop? You could have a leak at the brakes or air bag. Feel around the air bags as you can find a leak easily. Use a Dollar Store spray bottle with a soap solution to find other leaks. If no leaks and you are a DIY person, changing the governor as Brett says, is only a 15 minute job and EZ.

Pierce

Re: Building Air Pressure

Reply #4 –
Quote from: Greg & Erin Burress –
In the meantime, could I use my pancake compressor to charge the air tanks using the aux air compressor port in the engine?

Greg,

The short answer is Yes,  depending on where your air tap comes off or with some mods.

Now you need to think as to how long this compressor will need to run. Is it made for such a long run time as it no where has the volume as your engine driven air compressor.  You will also be adding wet air into the system which can cause more problems unless you rig up some kind of dryer.

Mike

Re: Building Air Pressure

Reply #5 –
Unless your check valves are shot or your system has been modified hooking up a compressor to the aux air fitting will only add air to the leveling system manifolds and through them to the air bags.  It will not add air to the HWH tank (if you have one) or to eith the front or rear service tanks or the wet tank.

The attached drawings are originally dated 7/20/94.  This drawing shows additions for a single slide.

Check near the back of your FT book for the air diagram.  If you don't have one check with FT and pay for a copy.  It is always good to know where to start.


Here is a way to add air to the wet tanks and service tanks. External Compressor Connection to Add Air to Wet Tank and Service Tanks

Re: Building Air Pressure

Reply #6 –
Thanks for all the responses. I went to NAPA and purchased a governor. By the time I got back to the coach, the outside temp had warmed to 45 and the pressure quickly went to normal with a little engine revving.  Once it reached 60, it quickly went to 105. During driving the pressure varies from 105 to 120 and drops to 90 during braking. I was able to make it back to Texas on Saturday, and am headed to MOT today for the to check it for leaks or governor.

Re: Building Air Pressure

Reply #7 –
Could be water in your air tanks or air system that froze with the low temperatures.  Did you drain your air tanks?

Re: Building Air Pressure

Reply #8 –
I haven't drained my air tanks. Good suggestion. I'll have MOT look at that too.

Re: Building Air Pressure

Reply #9 –
Greg, sounds like the heater element in the air drier failed and you had a purge valve frozen partially open?  When's the last time the drier was serviced?

Re: Building Air Pressure

Reply #10 –
Draining the tanks, should really only be considered a "report card" on the condition of the air dryer.

If anything but clean, dry air comes out the dryer has FAILED and needs immediate service/replacement.

Re: Building Air Pressure

Reply #11 –
Quote from: Pierce & Gaylie Stewart –
When you shut down with full pressure, how fast does the pressure drop? You could have a leak at the brakes or air bag. Feel around the air bags as you can find a leak easily. Use a Dollar Store spray bottle with a soap solution to find other leaks. If no leaks and you are a DIY person, changing the governor as Brett says, is only a 15 minute job and EZ.

Pierce


Reading "Traveling west in lower temps and higher elevations. Each morning air pressure is at 30 psi. It's taking me 1.5 to 2 hours to charge with higher idle." Makes the little man in my head scream.  Of all the responses to the original poster, no one said to stop driving until your air brake system is repaired.

Here's a basic daily check list for air brakes.

daily air brake inspection | DOT / CSA Insights: Success Ahead

"Air pressure build-up from 85 psi to 100 psi should take 45 seconds or less."

https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/brake_safety_systems_02-14.pdf

Re: Building Air Pressure

Reply #12 –
MOT fixed my air pressure issues.  Had to replace to the right rear height control valve and 2 drain valves.  The connections on both sides of the air regulator were cleaned and thread sealant used on the fittings, they also tightened 5 fittings leaking air.  How often do fittings need to be inspected and tightened?

Re: Building Air Pressure

Reply #13 –
Quote from: Greg & Erin Burress –
MOT fixed my air pressure issues.  Had to replace to the right rear height control valve and 2 drain valves.  The connections on both sides of the air regulator were cleaned and thread sealant used on the fittings, they also tightened 5 fittings leaking air.  How often do fittings need to be inspected and tightened?
I would do a check every 6 months.. depending on how much you move down the road.. Or when bored..I havnt been bored yet so I check about every 6 months!

Re: Building Air Pressure

Reply #14 –
Thanks David!!
 

Re: Building Air Pressure

Reply #15 –
Shouldnt take but a few minutes to spray it down and a quick look around.