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conseils d entretien 1366 x 500

Maintenance advice


NHP dans le détails

Maintenance of the HP washer is essential :

  • Combustion engine :
    • 1st oil change : after 10 hours max.
    • Other oil changes : every 100 hours

  • Pump : 
    • 1st oil change : after 50 hours max.
    • Other oil changes : every 250 hours

Fore more information, refer to the instructions manual.

Oil quality for the pumps :

  • Annovi Reverberi, Interpump, Udor pumps : SAE15W40
  • Bertolini pumps : SAE80W90
  • Never let the HP washer work in closed circuit during more than 2 minutes.

  • Define precisely the size of nozzles :
    you need to know the flow rate and the pressure.
    Refer to the nozzles table.

  • If the water is not clear (sand ; debris), protect the HP washer thanks to a bowl filter with rinceable cartridge.

Warranty :

1 year or 2 years for parts and labour depending on the model
provided the machine has been used and maintained properly
(wear parts and washing accessories excluded)



puce rouge A reliable electrical installation

The quality of the power supply affects the life of the motor. If you use an extension cord, it must be of the right section, and in good condition. It must also be unrolled in its entirety, so that the cable does not rise in temperature, which could lead it to melt and could create a short circuit, thus burning out the electronic components of the HP washer, or even the electric motor.

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puce rouge.png Feed with clean water

The longevity of a high pressure washer depends on a good water supply. A clogged filter leads to a sudden loss of pressure. It is essential to keep the filter clean and in good condition, and to check it on a regular basis. If the water flow is insufficient, the pump will cavitate because it is sucking in air, leading to premature deterioration. Water hammers damage the suction and delivery valves. They also damage the piston seals.


puce rouge.png Keep the valves tight

The valves of a HP washer can be compared to the valves of a combustion engine. They control the inlet of water and its discharge under high pressure. If they are not perfectly sealed, the pump loses performance. Their replacement is recommended every 1000 hours, depending on the model, or once a year. Their normal wear results in a gradual loss of pressure over the months, because their springs are worn out and their cups are no longer perfectly sealed on their seat. The valves are sensitive to impurities and temperature rises. Their plastic body is distorted beyond 55° C. On HP washers not fitted with automatic shutdown, it is therefore important not to let the engine run for more than two minutes in closed circuit (without using the lance), in order to avoid overheating. If, after replacing the valves, the HP washer still does not bring the right pressure, the problem can be a broken piston or the wear of its seals. The replacement of these components is the responsibility of a specialized repairer.

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puce rouge Change oil at least once a year

The high pressure pump of professional HP washers has, like a combustion engine, a crankshaft and connecting rods. There are also pumps with axial pistons coupled to a swash plate, a principle similar to the hydraulic pump. These mobile assemblies are lubricated and cooled in an oil bath. A first oil change after 50 hours of use is necessary to clear the impurities resulting from the running-in. This is inexpensive because the oil used is usually SAE15W40, a common viscosity. The pump casing must then be emptied periodically, every 250 hours or at least once a year, according to the recommendations of the manufacturers. If the oil removed shows a mayonnaise color, the oil seals sealing the piston base are likely to be damaged. In this case, it is mandatory to replace them to avoid breaking the pump. This intervention must be delegated to a specialized technician.



puce rouge The importance of the nozzle

The nozzle at the end of the lance is a wearing part. Its size is determined by the water flow and the maximum working pressure of the HP washer. It is therefore important to use the correct model and not to interchange the nozzles of two machines with different performance. If the orifice is too large, the HP washer will not build up pressure. Conversely, an undersized nozzle will not let all the water flow pass. In this case, the pump builds up too much pressure and heats up abnormally, leading to deterioration of the valves and seals. The nozzle is particularly sensitive to clogging and should not be left on the ground, at the risk of loading it with soil. You must also be careful with the high pressure hose and not allow foreign bodies to enter it that could clog the gun or the nozzle, which are frequent causes of failure.


puce rouge Do not unsettle the by-pass regulator

The factory-set bypass regulator controls the operating pressure. This valve recycles a precise quantity of water to the pump when the lance is closed on HP washers not fitted  with an automatic shutdown. Its setting must not be changed under any circumstances, at the risk of serious consequences for the HP washer : if the by-pass regulator slows down the passage of water too much, the pressure rises excessively in the pump, which heats up, leading to the deterioration of its seals. Even worse, sometimes the valve caps can give way and fly off like a bullet, at the risk of seriously injuring the operator. In addition, with a correctly set bypass regulator, it is important not to leave the HP washer run for more than two minutes without using the lance. The circulating water rises in temperature again and can reach 60 ° C. When starting washing again, the cold water entering the cylinder head creates a thermal shock, sometimes causing the pump or the pistons, which are often made of ceramic, to break. It is therefore important to choose a HP washer with an automatic start and stop feature.

puce rouge Prevent freezing

The pump cylinder head is frost sensitive. To prevent damage, it is important to purge the pressure washer after use. To do this, remove the water supply hose and the high pressure hose, then run the HP washer for 3 to 4 seconds to purge it. This operation is not sufficient in severe frosts, as there is always some water left in the cylinder head. This can crack under the effect of freezing temperatures. It is then essential to store the machine in a temperate place.

Avoid fouling up hot water HP washers

In hot water HP washers there is a small boiler running on domestic fuel. They usually have a strainer and a filter to be checked periodically. After use, it is important to stop the production of hot water by setting the thermostat to zero a few moments before turning down the HP washer. This manipulation ensures gradual cooling with cold water and extends the life of the coil. It is essential to purge it during periods of frost to avoid bursting the coil. Moreover, the hot water HP washer must be installed in a place ensuring the evacuation of burnt gases, as recycling them causes poor combustion.