Maintaining Your Air Cooled Reciprocating Air Compressor

By In Information On March 18, 2016

In our last blog post, we discussed essential maintenance for rotary screw air compressors. That type of compressor operates at 30 horsepower or higher, and that amount of power makes these machines suitable for industries like mining and factory work.

Another type of air compressor that requires maintenance is a piston air compressor, also known as a reciprocating air compressor. These machines operate at a lower horsepower than rotary screw compressors do. Despite the lower horsepower, piston compressors remain reliable and useful for many applications.

Read on to learn the vital maintenance tasks all piston compressors need performed on a regular basis. If you aren’t familiar with piston compressors or how to perform maintenance tasks, rely on an air compressor expert or a similarly competent professional.

Why Piston Compressors Need Maintenance

The inside of a piston compressor bears many similarities to an internal combustion engine. The main parts include a piston head that rises and drops as a crankshaft rotates. There are also numerous valves, plates, rods, and gauges that keep the machine working properly.

All these moving parts can wear down or become dislodged with regular use. The more you use your compressor, the greater the chances that it will develop problems. However, you can somewhat reduce its need for major repairs if you are diligent about maintenance.

Spending a little time on piston compressor maintenance now saves you time and money later. When your compressor stays in good condition, you can rely on it; it won’t stop functioning and halt your work. Regular maintenance also helps extend the life of your compressor, meaning you won’t have to replace it as often.

What Maintenance Steps to Take

Now that you’re armed with reasons to spend time on piston compressor upkeep, let’s learn what maintenance tasks you should perform. We’ll go over what you should do daily, weekly, monthly, and as needed.


Most of the vital maintenance to your piston compressor happens before you turn it on each day. Perform these tasks every time you use your air compressor:

  • Clean the unit. Wipe off any dust, grease, or grime.
  • Inspect the electrical wires. If you notice anything out of the ordinary, investigate further before turning the compressor on.
  • Look for loose components. If you find loose parts, tighten them.
  • Check the oil level (if your machine is oil lubricated).
  • Look for air leaks. Again, if you notice this issue, correct the problem before you use the compressor.
  • Inspect the air filter. Make sure it’s clean enough that you can use the machine safely and effectively.

These tasks seem simple, but don’t let their easiness lure you into skipping them. They only take one or two extra minutes on most days, so make performing them a habit.

Any time you finish using your compressor, you need to perform a few additional maintenance tasks. One important task is to drain the air tanks. To do this, first disconnect the power. Then open the drain so it slowly releases air. You can fully open the valve when the pressure in the tank reaches 10 psi. If you use an oil-lubricated piston compressor, properly dispose of any oil in the tank.

Depending on how much you use your unit, you may need to drain the air tanks periodically throughout the day as well. If you work in a high-humidity area, draining the tanks several times a day is recommended.


A piston compressor uses an air filter to ensure that miniscule contaminants stay out of the compressor’s air supply. The filter traps these particles and keeps them away from the machine’s vital parts.

Because a piston compressor pushes so much air through itself and therefore through the filter, you should check the air filter weekly. Your compressor likely has a reusable filter that you can clean. If you notice that the filter becomes particularly filthy or that it has sustained damage from use, replace it with a new filter.


Another vital component of your piston compressor is its safety release valve. This valve constantly measures the compressor tank’s pressure when the machine is in use. If the pressure reaches a preset limit, the safety valve activates and stops the motor.

You should check this part’s function at least once a month. You may want to test the safety valve more often, depending on how much you use your compressor.

To check this part, empty the tanks and disconnect the compressor from all power sources. Next, pull the release valve several times in succession. This action dislodges any debris that may be blocking the valve. Watch for the plunger to move in and out. If the plunger does not move, it’s defective, so replace it with a new valve. Purchase a valve that is ASME certified to ensure maximum efficacy.

When you perform your monthly piston compressor inspection, also look at its drive belt. Attach a belt tension gauge and compare the reading to the optimal reading listed in the compressor’s manual. If the reading is low, tighten the bolts on the motor. Loosen the bolts if the reading is high.

As Needed

If your piston compressor is oil lubricated, you’ll need to change the pump oil at least once a year. You also want to change the oil anytime it becomes contaminated, so check the oil periodically. With the compressor off and disconnected from power, insert a clean screwdriver into the crankcase. Remove the screwdriver and inspect the oil on it. If you see dirt or other debris, you should replace the oil.

When it’s time to replace the oil, use the type of oil recommended by the manufacturer of your compressor. If you use an oil with a viscosity that’s too high or too low, your compressor could sustain permanent damage.

Less often, you’ll need to remove and clean parts like the piston and the piston rod. You can use soapy water and a wire brush on any hard parts, but avoid using the wire brush on softer, more flexible parts or any parts made with Teflon or brass. If any parts appear worn, replace them with new components.


If you want your piston compressor to last for years, perform these maintenance tasks regularly. If you have additional questions about caring for your compressor, speak to a compressor expert.

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