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Reliable, this machine requires little maintenance. Unless it has not worked for some time and the available pressure is not what it was... The operation then runs without difficulty with a current tool.

Descale a pressure washer

Practical advice

When the head of the group has been removed, keep the body of the engine upright otherwise the oil will spread. This lubricant can, however, give way to ordinary engine oil (type 15W40).
● Cylinder head and piston holder are often "glued", do not try to separate them with a screwdriver blade because the plane of joint, perfectly rectified, would be damaged. Instead, tap the two pieces with a mallet.

As the name suggests, a high-pressure cleaner allows to have a hundred bars out lance. If this is no longer the case, the inlet and outlet valves are probably faulty, that is to say scaled... This problem is especially encountered on devices that have been inactive for a long time, without having been purged. The limestone is then deposited on the famous valves and their seats, in the cylinder head. Other causes are possible, especially when the pistons are not ceramic. For reasons of cost, many consumer devices are indeed satisfied with pistons made of chrome steel or stainless steel. These are subject to scratches (under the effect of hard particles in the water) that cause a loss of pressure.

Disassemble the cleaner

The cladding of our appliance is removed by removing a few Phillips screws. We then discover the group formed of the electric motor with, at the end, the pump head. This is fixed to the motor by four Allen screws. Their loosening will be facilitated by injecting a little releasing agent because the oxidation tends to seize them in the aluminum of the crankcase. Tapping the head with a rubber mallet, it detaches and makes the pistons appear with their return springs. The head separates itself in two with one side, the piston holder and the other, the breech. The six flaps become accessible and pull out of their housings without tools.

Descale valve and valve

Plastic, each intake or discharge valve is composed of two parts nested one on the other: the base and the valve.

• The base, provided with two O-rings, thus seals in the housing while the valve comprises a valve. Pushed by a spring, it is kept pressed against its base seat.

• In contact with each other, these pieces are exposed to scale that takes the form of whitish crystals. Bases and valves are immersed in alcohol vinegar until the disappearance of this scale. Less corrosive than a hydrochloric acid solution (even very dilute), vinegar is preferable because it will not attack the springs. This descaling is followed by rinsing the parts under the tap.

Winding the engine

After cleaning their housings in the piston holder and the cylinder head, the valves are simply re-fitted. When reassembling the cylinder head and the piston holder (without seal), the valves must be put in place without forcing. Thus reconstituted, the pump head is ready to find its place at the end of the engine. To do this, you must press the head to overcome the resistance of the springs and replace the four screws; Then lock with an Allen key. The intervention ends by closing the dressing.

Disassemble the motor pump

Disassemble the motor pump

Remove the cladding and place the pump set in a container (oil can leak). Unscrew with a hexagon key the four screws of the head. Then peel it off with a rubber mallet.

Piston holder and cylinder head

Piston holder and cylinder head

The head comprises two parts, the piston holder and the cylinder head, separated by the joint plane. The three pistons, here steel, are each equipped with a return spring and a lock washer.

Remove the lock washer

Remove the lock washer

This throat washer rests on the balls of a bearing. Below, a cam driven by the motor, communicates to the washer an oscillating movement, which is transmitted alternately to the pistons.

Remove the valves

Remove the valves

After opening the head, the piston holder is here on the left and the bolt on the right. Mounted in housing that extend on either side of the joint plane, the six valves are removed by hand.

Separate the flaps

Separate the flaps

Separate the two parts of each valve: at the front, the O-ring base and at the back, the valve that rests on the seat of the base. Gently test its travel with a small screwdriver.

Descale the flaps

Descale the flaps

Soak the flaps in a container filled with alcohol vinegar (acetic acid). It neutralizes the limestone but its action is quite slow because it is a weak acid. Then rinse with water.

Refit the flaps

Refit the flaps

After cleaning the cylinder head, replace the valves in their housings (in the correct direction). Preferably, place them all on the same side even if, at the disassembly, they were distributed in both rooms.

Reassemble the cleaner

Reassemble the cleaner

Reassemble pistons holder and cylinder head making sure each valve stays in place. Place the head on the housing, press to compress the springs and lock the four screws.


Video Instruction: Hydrotek Hot Water Coil Cleaning, Also Known As De-Scaling (Pressure Washer)