Symptoms Of Bad Air Governor – Important Things You Should Check

There are a few symptoms of bad air governor that you need to keep an eye out for.

But before we proceed to this topic, you may be wondering how your air governor even works. This will give you a better understanding of its operation and what can go wrong at times. 

So, to learn more about this component and what you should do to ensure its performance, keep reading to gain an understanding of this essential portion of your vehicle. Let’s get started.

symptoms of bad air governor

Symptoms Of Bad Air Governor

Basically, your air governor functions by utilizing compressed air instead of hydraulic fluid. The compressed air used by the system originates from an engine-mounted type of compressor. Then, this part pumps air through your air lines and then to your storage air tanks. This is where it is kept until needed by your truck.

Because of this function, you can expect to get ample supply of air when there is a need to hit your emergency brakes.

It is also important to note that your discharge lines are a key component, and this helps your oil vapor, water vapor, and air mixtures to get cooler between your air dryer and compressor. With this in mind, you may be wondering about the length of time for the semi-truck to produce air pressure. 

For the most part, it can take about 45 seconds or quicker for air compressors to obtain adequate pressure buildup that ranges from 80 up to 135 PSI. But with the differences in every vehicle, it is still important to determine what is the desirable air pressure that your truck needs. 

And this brings you to an important question – why do some trucks fail to build pressure. When your truck is not building ample pressure, it can be caused by a stuck unloader valve. But if there is too much pressure, and yet it does not kick in your compressor, your air governor is to blame. 

You may also want to inspect for possible leaks, as well as your service and emergency lines. These are common components that may experience some issues, which you need to pay close attention to. 

Your truck’s unloader valve is an essential component for your air brake system. This releases air that is trapped on the inside part of your tank. So, because of this component, it is possible for your motor to restart after every cycle. 

But not many people are aware of the issues that can arise with the unloader valve. In fact, it is quite common, particularly for EGR trucks. The reason for this is that such trucks typically generate far too much carbon. Then, this component builds up onto the valves. 

Thankfully, you should be able to fix this concern temporarily. It only takes a few steps to make it happen. You can begin by opening your hood and then locating your unloader valve. Afterwards, tap on this component using a hammer as this allows your truck to generate ample air required for the next stop.

You may have to wait for a few minutes before air pressure can accumulate. Then, you should be able to start your vehicle and drive it to the closest destination.

When you have arrived at your stop, you can now clean your valves. In case you have your rebuild kit for the unloader valves, you should place the brand new equipment included such as the O-rings and the gaskets.

Do keep in mind that caution is very important when you are cleaning your valves. Begin by unscrewing your top bolts with a 9/16 type of wrench. Remove the lid and use some needle-nose pliers in pulling your unloader valves out.

Once you have taken out the unloader valves, check the status to make sure there is no damage. Then, clean the valves with soapy water or some kind of carburetor cleaner. You can also use this type of cleaner on your valve holes, as this should eliminate the grease. 

Use compressed air as a final cleaning technique, which should get the holes even cleaner. Then, spray some lubricant on the valves to finish off. Put the valves and your lid again, and then make the bolts tighter. 

Now, when it comes to checking the quality of your air brake governor, there are a few things you can do to make this happen. Considering the fact that compressors in your air brake system function each time you run your vehicle, the governors are much needed for controlling the system. So, when the governors are not working properly, the air emitted by the compressor can cause some issues to you.

Hence, when you have a faulty governor, the air pressure released may be zero to just very little. Considering how dangerous air governors are, you need to test these components as a part of your pre-travel inspection. You may also need to follow some other techniques including following the oil change schedule and ensuring the vehicle’s fuel economy.

There are two tests required for the air governor. These are performed to determine if your governor is capable of putting compressing in your unload and load phase.

Start by pumping this down to around 80 PSI. Follow it up by throttling the truck slightly and check if you notice an increase in the needle’s climb. If so, your compressor is currently in the load phase.

Now, you would want to determine if your compressor is capable of going from the load to unload phase. This time, pump your truck up to the maximum pressure. After you have reached the highest point, this should purge the air dryer and you will notice the needles are no longer climbing. You should also pay close attention to the sound of the governor – it should be barely audible as you perform the test.

Typically, you may observe the maximum pressure to be at 105 to as much as 135 PSI.

While you are at it, you may want to check for other symptoms of a bad air  governor, which means the compressor requires a replacement. 

  • Fast cycling coming from your wet tank
  • Percussive sound originating from your safety valves
  • Air gauges remain still for quite a while
  • Your vehicle builds too little or too much pressure.

With all these things in mind, you need to get these symptoms addressed in case bigger problems arise.

Final Thoughts

There are some symptoms of bad air governors to pay attention to, so you can avoid further problems. Consider these tips to determine if yours is doing the way it should.

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