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Step by step guide

Evolution 10 year service - P90

Servicing our pressure washers are quite straight forward and could be done by most people by following the step-by-step instructions in this manual.

Please go trough the whole manual before starting work on your pressure washer to make sure you understand the procedure and that you have the necessary tools to complete the task.

Always unplug the pressure washer from both the mains power and the water outlet before starting the service.

Even though power and water is disconnected there may be pressurized water in the hose. Discharge this pressure by pulling the trigger on the gun.

Make sure your work area is clean and appropriate for the work you are about to do. There will usually be a small amount of water inside the pump and hose.

If you are doing a 10-year service, then be prepared to collect the used oil from the oil chamber. Please dispose of the oil in accordance with local law and regulations.

ISO 46 hydraulic oil can be substituted with similar non detergent oil of the same viscosity.

00. Parts and tools

An overview of what is needed to do this service.

01. Remove water filter

Remove water filter by unscrewing it counterclockwise.

02. Remove the hose reel

Release the short pressure hose from the pump outlet. Unscrew the 3 T25 screws from the back cabinet. Take off the cover and the hose reel.

03. Remove screws from the back cabinet

Remove the power cable from the cable reel so you can access the two screws behind the reel. Unscrew the 11 T25 screws from the backside of the pressure washer.

04. Remove screws holding the motor

Unscrew the four 6mm Allen screws holding the motor to the back cabinet.

05. Lift off the rear cabinet

Put the pressure washer face down. Lift off the rear cabinet. Release the strain reliever and the power cord.

06. Remove screws from the pump.

Unscrew the 3 T25 screws securing the motor/pump.

07. Remove the water outlet

Use a flat head screwdriver to pry loose the U-pin at the pump head. Remove the U-pin and then remove the high-pressure water outlet.

08. Remove the motor/pump

Carefully lift the motor/pump out of the front cover. Turn it 180° before placing it on a flat surface. Remove the on/off button, its extension and the pump head cover.

08. Remove the switch box

Remove the switch box by pulling it in the direction indicated. It is press fitted onto the start/stop valve on the pump.

09. Loosen the screws securing the pump

Use a 6 mm hex/Allen key to loosen the 4 screws securing the pump assembly. Be ready to catch the oil from the oil chamber with a suitable container.

10. Remove the pump assembly

Rotate the whole pump assembly 15-20° counterclockwise to release it from the motor oil chamber.

Remove the complete pump assembly.

11. Inspect bearings

If the oil has a lot of metal particles in it, we suggest that you also remove the wobble plate assembly and visually inspect the two thrust bearings for damage. If there is no visible damage, clean the parts and oil chamber, and reassemble.

12. Reuse parts

If the service kit does not come preassembled, you need to split the old pump. Remove the four Allen keys keeping the pump together, and extract the six brass backing rings (pink) and the six plastic backing rings (blue).

13. Lubricate O-rings

Lubricate O-rings as indicated and then assemble the pump as shown.

14. Assemble the service kit

Assemble the service kit as illustrated. The start/stop valve (the white plastic nut with a metal protrusion on the pump head) should be aligned with the protrusion with a hole on the piston kit. Plastic backing rings are blue and brass backing rings are pink.

Tighten up the four Allen screws.

15. Refill oil

Refill the oil chamber with ISO 46 hydraulic oil or another non detergent oil with the same viscosity.

The oil should reach the top of the thrust bearing.

16. Fit the pump assembly to the motor

Before fitting lubricate the O-ring on the oil chamber with some of the hydraulic oil.

As soon as everything is aligned correctly press the pump assembly down own to the motor. A fair amount of force is needed as you are compressing the piston springs towards the wobble plate. When the two mating surfaces are in contact, twist the pump assembly 15-20° clockwise so that the two locks engage.

17. Secure the pump

Use the 4 short Allen bolts to sthe pump to the motor.

18. Reattach the switch box

Attach the switch box to the pump. You may need to put quite a lot of pressure to get the box firmly seated on the start/stop valve. It should pop into place.

19. Reattach the on/off button

Reattach the on/off button, its extension and the pump head cover.

20. Place the motor/pump unit back into the front cover

Carefully lift the motor/pump and turn it 180° before placing it into the front cover.

Make sure the on/off button and its extension are properly positioned so that they can operate freely.

21. Attach the water outlet

Attach the high-pressure water outlet to the pump head. Secure it with the U-pin. Some force may be needed to fully fit the U-pin.

22. Secure motor/pump unit to the front cover

Secure the motor/pump and the switch box using the 3 T25 screws.

23. Fit the back cabinet

Fit the strain reliever and make sure the power cord is correctly situated.

Place the back cabinet onto the front cover. Adjust so both parts align correctly. If you are having trouble to get a good fit, check that the power cables and motor cowling are aligned correctly.

24. Secure the motor to the back cabinet

Fix the motor to the back cabinet with the four remaining 6mm Allen screws.

If the holes does not align, remove the rear cabinet and readjust the motor/pump.

25. Secure the back cabinet

Once you are happy with the alignment of the back cabinet, secure the front cover to the back cabinet with 11 T25 screws.

26. Fit the hose reel assembly

Fit the hose reel assembly to the back cabinet.

Push the interconnect pressure hose into the depression.

Fit the cover and secure it with 3 T25 screws.

Connect the hose to the outlet.

27. Reattach the water filter

Check that the filter cassette is clean and without damage.

Reattach the water filter to the water inlet.

28. First start after service

Congratulations with finishing the service of your AVA product.

It is now time to do the first start after service.

  1. Start by connecting the pressure gun to the hose.
  2. Connect water.Make sure no water is leaking from the inside or anywhere else on the pressure washer.
  3. Pull the trigger and let the water flow until there is no more air coming out.
  4. Connect the power cord.
  5. Turn on the pressure washer.
  6. Pull the trigger and let water run for a minute before connecting a nozzle.
  7. Connect the nozzle.
  8. Use the pressure washer and make sure it is operating as normal.

29. Troubleshooting

Water is leaking from the inside
  • Disconnect the power and open the pressure washer to locate the leak.
  • Take necessary action to remedy any leaks.

Motor runs and won't stop when you release the trigger
  • This is most likely due to an improper seating of the switch box on the start/stop valve.
  • Open the machine and check that the switch box is correctly seated.

The pressure washer won't turn on
  • Check that the power cable is connected.
  • Check that the circuit breaker has not been tripped.
  • Check that the fuse in the power plug is intact (UK models only).
  • Open the machine and check that all the internal cabling is connected.

Poor performance/pressure
  • Improper assembly or dirt/debris in the pump.
  • Check that the pump and especially the main valve for foreign objects/debris.
  • Make sure that the spring in the main valve is correctly seated and working as intended.

Motor is making a humming noise and is not able to start
  • Check that the capacitor is connected to the motor.
  • It should be connected with one white and one black cable.