PRXB Exhaust Brake Slow to Release

[petersonj]

A little over a month ago I installed a new 4" in-line PRXB exhaust brake. It is installed just upstream of the muffler. The PacBrake kit included an air compressor, a 1/2 gallon air tank, and a air control valve.

The exhaust brake works very well, but with one minor exception - if the exhaust brake has been applied for approximately 20 seconds or longer, it is slow to release. This issue has been occurring since the first day of operation. It makes no difference whether the engine is warm or cold.

I am certain that the exhaust brake is not sticking mechanically because even when the release is slow, the air control valve hasn't release any air. When the control valve does release the air, the exhaust brake immediately releases. I have two switches to control the exhaust brake. The issue occurs regardless of which switch is used.

I am leaning toward a problem with the air control valve. The compressor cycles normally keeping air pressure in the range from 100 psi to 130 psi.

Has anybody had a similar experience? If so, what did you find?

- John

 

[Ozymandias]

Did you use the valve I posted a couple weeks ago?

 

[petersonj]

I was hoping that you would respond. I did not install the valve. I have purchased the valve, just not installed it. If I recall, you recommended the pressure reducing valve to a member because he was having times when his exhaust brake would not turn off at all.

I think you mentioned that you had a similar issue, too. What exactly was your issue? Did you talk to anyone at PacBrake about your issue?

I will install the valve tomorrow and see if it will help.

- John

 

[Ozymandias]

No I figured out myself.

To high of a pressure takes to long to leave the piston, if it is combined with a subpar or wrong valve with a small dump orifice you expirence a slow relief.

And just by experience i know that the valve from Amazon works great, combined with the pressure reducer to 100psi.

 

[petersonj]

And just by experience i know that the valve from Amazon works great, combined with the pressure reducer to 100psi.

I bought the pressure reducer valve that you mentioned. Did you also buy a directional valve from Amazon? If so, can you provide that valve information.

One other question. Did you place the pressure reducing valve right out of the compressor so that the whole system has reduced pressure, or did you place it just upstream of the directional valve?

I am a bit disappointed with some of the parts quality from PacBrake. I had an air leak in the system and the rate of leakage was not consistent. It took a few days to find it because the leak was an internal leak inside the check valve right at the compressor. When I bench tested the check valve for back flow leakage, it was inconsistent. Also, the free flow direction was very restrictive. I found this out when I installed a quality replacement check valve. The "compressor on" cycle time was significantly reduced.

Appreciate your input.

- John

 

[Ozymandias]

Install of it.

The valve
>>>>TAILONZ PNEUMATIC 1/4"NPT Solenoid Valve 3V210-08 DC12V Single Coil Pilot-Operated Electric 2 Position 3 Way Connection Type(Junction Box)<<<<

Sorry for not posting direct link, just dial it into Google, first result is the right one.

 

[petersonj]

And just by experience i know that the valve from Amazon works great, combined with the pressure reducer to 100psi.

My two-way directional valve should be arriving today. I will be installing it today.

When you installed your two-way directional valve and your pressure reducing valve, did you do the installation one component at a time and then test the system, or did you install everything in one event and then test the system?

Edit: I may have answered my own question. I noticed that the two-way directional valve states "116 psi maximum operating pressure". So, I installed the two-way direction valve and the 100 psi reducing valve, as well.

So far, the testing after installation has shown that the exhaust brake "not releasing" issue is gone. I will give it a good road test drive tomorrow, after making a mount for the new hardware.

Ozzy, thank you for your help.

- John

 

[Cummins12V98]

We need an “OZZY To The Rescue” section on the TDR.

 

[Ozymandias]

Now I'm blushing.

Good that it works now, and yes I installed all in one go.

 

[Topzide]

We need "The RAM Trucks" repair volumes by @Ozymandias!
He is such a resource for us, he's seen it or been there with his rig and the travels that he's gone on!

 

[petersonj]

So, I installed the two-way direction valve and the 100 psi reducing valve, as well.

So far, the testing after installation has shown that the exhaust brake "not releasing" issue is gone. I will give it a good road test drive tomorrow, after making a mount for the new hardware.

This is a follow up on the test drive and several days of operation. For sure, the original problem of the "slow release of the exhaust brake" is gone, but a different issue popped up - the compressor immediately cycles "on" the instant the exhaust brake is applied - every time. The compressor runs for about 3 seconds and then cycles "off".

Previous to changing out the directional valve and adding the 100 psi pressure reducing valve, the compressor would cycle "on" with the third application of the exhaust brake, which I considered to be normal. I determined that the cause of the instant cycling was from the combination of the condensed mounting design of the compressor, pressure switch, and directional control valve all right next to each other, plus a "faster opening" new valve.

I left the components in the same location, but I removed the "T" fitting that joined the compressor outlet / pressure switch to the directional valve. Basically, I plumbed the compressor / pressure switch straight to the air tank and then plumbed a second line from the air tank back to the directional valve. This corrected the instant cycling.

While I was doing the project, I decided to get rid of the compressor mounts - three rubber mounts with steel sleeves and through bolts and nuts. The design did nothing for stopping compressor vibration from being transferred to surrounding components. I purchased true vibration isolation mounts and installed them - what an improvement.

- John