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Compressor Overhaul: What You Need to Know About Rebuilding a Compressor

It is worth knowing what is needed when rebuilding a compressor since an overhaul can save you the time and resources of getting a replacement in the long run.

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A new compressor certainly has its advantages, but that does not mean an existing one cannot be made to look new-like, which is where an overhaul becomes needful.

In that regard, a compressor that has failed or whose major component such as a motor is faulty can still be inspected and repaired, whether it is a reciprocating or rotary compressor.

It will take the expertise of reciprocating technicians to work efficiently on these mechanical components to minimize outages and prevent further degradation.

That being the case, the various services that can be implemented when rebuilding a compressor include:

  • Crankshaft repairs
  • Repair or replacement of parts
  • Alignment of the gas cylinder and mainframe
  • Inspection or overhauls of the gas and crankcase
  • Line bore of the mainframe


What is Compressor Overhaul?

Compressor overhaul is the process of taking apart the components of a compressor in a bid to examine it thoroughly and repair it if need be.

Due to the high cost of buying and maintaining a compressor, it may not be ideal to replace it entirely once it encounters issues.

The latter can be attributed to the more expensive cost a new compressor will attract, which makes a screw compressor overhaul a cheaper and affordable alternative.

That being the case, rebuilding a compressor is a solution that will see components of the failed valve restored in good working condition.

All it’ll take is the simple process of a compressor valve rebuild to restore the entire operation of the machine to normalcy.


What You Need to Know About Rebuilding a Compressor

Compressors like the rotary screw compressors may not have defects in their internal components.

The lack of internal wear increases the compressor’s potential for its high-level performance to be restored through a rebuild.

However, you need to check whether the compressor is currently at a state where an overhaul will do it a lot of good, or you’re better off getting a replacement.

This check can be carried out by troubleshooting the compressor problems.


How to Diagnose Compressor Problems

There’s no technician at bay, and you’re uncertain if your compressor needs a rebuild or repair, then knowing how to diagnose compressor problems will help you out.

You can do it yourself and then draw the attention of an expert if you suspect that the components are malfunctioning.

In this case, you’ll be relying on the symptoms of a failing compressor to determine the state of yours.

Therefore, consider the following:

  • Disconnect and lock electrical supplies before carrying out an analysis.
  • Ascertain if there is a loss in lubrication.
  • Inspect the compressor’s oil if there are contaminants by draining the separator tank to its bottom.
  • Check if there is a sludge within the system.
  • Inspect the control circuit, relay timers, terminals, wires if they are overheating.
  • Determine if the refrigerant is not moving within the compressor properly.
  • Ascertain if faults are triggered by the compressor’s valve.

If either of these is noticeable, then compressor valve rebuild is what your machine needs.


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How to Rebuild a Compressor

The process of rebuilding a compressor is time-tasking that is why it could take several hours to be completed.

A knowledgeable mechanic will carry out the following processes while trying to overhaul a compressor.

Step 1. Separate Mechanical Components

The compressor’s valves, piping, separator tank, and other mechanical components will be disassembled.

Next, each will be cleaned thoroughly.

Step 2. Inspect Each Component

Parts that are worn out will need to be replaced, but before then, there is a need to determine which of them are strained. These could be the V-belts, O-rings, gaskets, etc.

Similarly, lubricating parts will need to be lubricated as specified by the equipment’s manufacturer. Special care and attention have to be given to the valves in the compressor’s oil circuit.

Step 3. Reassemble Mechanical Parts

The mechanical parts can now be reassembled with the filters replaced.

Step 4. Replace Compressor’s Lubricant

There is also a need to replace the compressor’s lubricant with a proper one.

However, the refilling has to be carried out based on the instructions specified in the Operation & Maintenance Manual.

Step 5. Test the Control Circuit

The compressor’s control unit also needs to be tested to identify malfunctioning electric components that may have not been spotted in the first inspection.

The test can be carried out through the process of dry running. In this case, you can operate the control unit without the motor and other higher voltage circuits.

Step 6. Initial Start-up

After the overhaul process, the initial start-up of the compressor is just as important, which brings about the need to turned it on carefully.

Step 7. Verify the Proper Rotation of the Motor

The motor needs to run in the right direction before the compressor is operated.

This check can be carried out by starting and stopping the motor immediately to take note of the direction it rotates.

Step 8. Start the Compressor Following Manufacturer’s Guide

Finally, you can turn on the compressor following the manufacturer’s directives in the Service and Parts Manual. Once it has been turned on, take the time to monitor its temperature and pressure.

A pressure that is higher than its rated pressure requires an adjustment using the pressure switch or complete shut down of the machine. Similarly, you need to shut down the compressor if there is a quick rise in temperature above 200° F.

The rapid rise is an indication of problems in the oil circuit, which needs to be fixed since restarting the compressor occasionally can lead to more problems.

Step 9. Flush the Oil Circuit

The new compressor oil needs to be flushed while the new filters that were installed need to be disposed of.

These steps are essential since there could still be contaminants such as dirt and varnish in:

  • Oil journals
  • Fittings
  • Piping
  • Other areas which can cause component failure

The oil circuit can then be wiped completely using appropriate compressor flush.

The flush can be carried out thrice or four times while the oil is changed in between flushes until there are no signs of varnish.


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Compressor overhaul through the process of rebuilding can restore proper function to an existing machine.

It does so at less the cost of buying a new one, and as a result, this saves you the extra cost of dishing out money for a new one.

Nonetheless, it is safe to point out that the steps to rebuild a compressor as outlined above are best carried out by a professional who has garnered experience from overhauling compressors.

Employing the services of a technician will ensure that your aim to get a fully functional compressor is achieved and other problems do not emanate after the overhaul.

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