When

To replace the piston seal

Tools required

  • Screwdriver, Torx T30

  • Seal-handling tool

12123
Figure: Seal-handling tool (left: closed tool; right: open tool)

No.

Description

1

Removal pin

2

Insertion pin

3

Knurl for opening and closing the seal-handling tool
(opening and closing is required only when using the removal pin)

Preparations

  1. Remove the pump head. See Removing the Pump Head.

  2. Remove the piston for which you want to replace the piston seal. See Removing the Pistons.

Parts affected on the pump head

1234576
Figure: Piston seal (here: for left piston)

No.

Description

1

Pump head

2

Piston seal

3

Support ring

4

Pump head seals (for seal wash plate and seal wash plate screws)

5

Seal wash plate

6

Screws, seal wash plate (4 screws)

7

Piston

Follow these steps

  1. With the screwdriver, remove the screws on the seal wash plate.

  2. Figure: Screws on seal wash plate (here: left plate)
  3. Remove the seal wash plate from the pump head.

  1. If one or more pump head seals come off when you remove the seal wash plate, keep them for reinstallation.

  1. Remove the support ring: Push the insertion pin of the seal-handling tool at a slight angle into the pump head. Do not use the removal pin.

Figure: Support ring (here: for left piston)
  1. Remove the tool. The support ring is removed together with the tool.

    Keep the support ring for reinstallation. The support ring is not a wear part and needs not to be replaced whenever you replace the piston seal.

  2. Open the seal-handling tool and push the removal pin into the pump head as far as the pin goes in.

  3. Figure: Piston seal (here: for left piston)
  4. Close the seal-handling tool and remove the tool from the pump head. The seal is removed together with the tool.

  5. To remove the seal from the seal-handling tool: Open the tool and pull off the seal from the tool. Once the seal has been removed, it cannot be reused.