Do-it-yourself compressor repair: malfunctions and how to fix them

Recommendation points

• Receiver does not maintain pressure when power is off
• Engine does not start
• No pumping occurs
• Unjustified overheating of the unit
• Outlet air contains water particles
• Repair of the crank mechanism of an automobile compressor
• Overheating of the compressor head, oil leaks
• Remove the front compressor cover
• Removing the oil pump
• Assembling the oil pump, installing the oil seal
• Replacing the oil filter and assembling the compressor
• A little about service

Compressors for painting a car, inflating tires or pneumatic tools need regular inspection, maintenance and sometimes repair. This is especially true for reciprocating compressors, in which pistons, rings and other parts require frequent replacement. We will talk about the main problems and how to fix them..

The causes of compressor malfunctions can be forced operation, neglect of service times, design defects, natural wear and tear of operating equipment. So that the broken unit does not slow down the work, we will try to understand the reasons for the failure and correct the situation by doing repairs ourselves.

Receiver does not maintain pressure when power is off

A decrease in pressure in the receiver when pumping is stopped indicates that there is a leak somewhere in the system. A soap solution applied to the likely places of leakage will help to detect it:

• compressed air line;
• piston head valve;
• receiver pressure relief valve.

A detected line leak can be sealed with tape and sealant. The valve must be screwed in all the way and, if the soap solution continues to bubble, the valve is faulty and needs to be replaced. Installed with a sealing FUM tape. If both the route and the valve do not show a leakage, it can be concluded that the problem is in the piston head valve. To get to it, you need to bleed all the air from the receiver and disassemble the cylinder head. If after cleaning the valve it does not restore its functions, then it will have to be replaced.

Engine does not start

The first thing to check is the mains voltage, the integrity of the connecting cable, as well as the quality of the contacts. Then check the fuses and, if necessary, replace them with similar ones. A blown fuse can also occur if it is installed with an unreasonably low response threshold. In this case, they must be replaced with the appropriate ones for your equipment. If, when installing new fuses, they blow out again – look for the cause in a short circuit.

Another reason may lie in the incorrect settings of the pressure switch on the receiver. To test this assumption, you need to bleed air from the tank and try to start the engine again. If it starts working, change the settings on the pressure switch.

Sometimes the engine starting is blocked by the overheating sensor during intensive continuous operation of the compressor. In this case, you need to let the equipment cool down, after which it will work again in standard mode..

No pumping occurs

In a situation where the engine is humming and no pumping occurs, the problem may be on the network. If the voltage drops below 220 V, the engine may not have enough power to operate the compressor correctly. In this case, you can install a stabilizer in the network or, if the phase is overloaded, temporarily disconnect the electrical devices connected to it from the power supply..

If the voltage is not too abnormal, it is possible that the pressure in the receiver is too high and resists pumping. In this case, the foremen recommend to turn off the compressor for a while and start it again after 15–20 seconds. If work is not restored, you need to check and, possibly, replace the pressure switch.

Pressure switch

Another reason could be a clogged by-pass valve, which should relieve excess pressure. In this case, remove and clean it. If the valve is destroyed, it must be replaced..

In some cases, the reason may be incorrect operation or malfunction of the voltage relay. It is difficult to repair it yourself, and if it is not possible to contact a service center for repair, you can replace it.

Unjustified overheating of the unit

The operation of the automatic thermal protection is understandable in cases when the room temperature is elevated, there is a reduced mains voltage (check with a multimeter), or the installation works without interruption for a long time.

If everything is in order with the room temperature, voltage and operating mode, then the filter installed at the atmospheric air inlet is clogged. The filter must be cleaned, rinsed, dried and reinstalled. Such manipulations must be performed regularly, with constant work – daily. This reduces the load on the compressor motor, reduces overall system wear..

Outlet air contains water particles

When painting works, this situation leads to the rejection of the painted surface. The reasons for its occurrence can be:

• the water from the receiver has not been drained for a long time;
• contamination of the inlet air filter;
• high humidity in the workshop.

The problem is solved depending on the cause of the occurrence. The accumulating water must be regularly removed from the receiver using the drain valve. The supply filter is cleaned or replaced. High humidity in the room can be dealt with by ventilation equipment or by installing additional moisture separators..

Filter drier

Repair of the crank mechanism of an automobile compressor

If the crank mechanism fails, it must be disassembled and the loose crank hole restored. To do this, a new thread is cut taking into account the fact that the motor shaft rotates counterclockwise..

Overheating of the compressor head, oil leaks

Possible causes of the problem are:

• defects in piston rings;
• oil contamination;
• hauling connecting rod bolts;
• insufficient clearance at the joints of the piston rings;
• loosening studs.

Oil leaks may require replacement of a worn oil seal. It may also come time to clean or replace the oil filter, replace the retaining ring. To do this, the compressor will have to be disassembled.

Remove the front compressor cover

It is necessary to unscrew the fastening bolts on the front cover of the compressor and remove the guide pins with a return hammer. After that, screw in the guide pins and push the front cover of the compressor on them.

To remove the front cover, you need to unscrew the oil supply pipe with an open-end wrench.

Removing the oil pump

From the front cover, you need to unscrew and remove the oil pump gear, gaining access to the bearing and removing it manually.

After that, you must carefully remove the retaining ring and knock out the oil seal.

To remove the locking sleeves, you need to warm up the installation site over the electric stove. Due to the different thermal expansion, the sleeves can be removed more easily.

After that it is necessary to remove the oil pump and remove and replace the oil filter.

To check the quality of the oil, you need to remove the rear cover of the compressor and check if clean oil is supplied to the gears through the oil supply hole. The oil must be free of foreign matter.

Assembling the oil pump, installing the oil seal

We start assembling the oil pump. At the first stage, we collect the sleeve.

After that, you need to install the bearing and bushing in the seat. Install the pump.

You will need mandrels to install the oil seal. Masters recommend using an anaerobic adhesive fixer. Check the seal for integrity, burrs or other damage. Clean the installation site with a clean, lint-free cloth. Install the packing ring and packing mandrel. Slide the oil seal into the seat. Remove the protective ring and mandrel. Install a new retaining ring.

Replacing the oil filter and assembling the compressor

To install the front cover, you need to align the guide pins and slide the cover. Screw on the oil supply pipe and seat the cover bolts on the adhesive sealant.

Next, insert the oil filter and reinstall the rear cover. Assembly completed.

At the end of the review of repairs, we suggest you watch a video about compressor repair.

A little about service

Periodic maintenance is required to keep the equipment working as expected. So, it is recommended to change the oil every 500 hours of operation, but at least once a year, provided that a high-quality and recommended brand is used. In home-made compressors, you do not need to seal the oil filling pipe, this will facilitate its replacement in the future. Check the oil level for possible leaks and burnout. As it gets dirty, the protective grille must be dismantled and cleaned. Check grounding periodically to avoid personal injury and equipment damage.

You also need to periodically inspect the valves – clean with a solvent and polish if necessary.

Drain the receiver regularly and clean the safety valve and air inlet filter. This will protect your compressor from premature wear. Performing these manipulations on a daily basis, you yourself can establish the optimal regularity of these actions for your conditions and volume of work. If the compressor has been idle for a long time, it is recommended to clean and lubricate the parts before starting. The implementation of these preventive measures will prevent or delay the breakdown and repair of the installation, extend its service life..