Fuel filter (VW Golf 1)

The high-pressure fuel pump of the described diesel models is very sensitive to contamination in the fuel. Another factor that interferes with operation is water. Water gets into the fuel mainly due to condensation in the fuel tank or in the fuel dispenser. Liquid and solid foreign substances must settle in the filter before the fuel gets to the high-pressure pump. The fuel is filtered in the fuel filter. The illustration shows a section of the filter, its installation with the Bosch fuel pump. The lower part of the filter has a replaceable element. Dirt particles settle on it; and do not enter the pump. Water can settle in the free cavity below, since it is heavier than the fuel.

Manual fuel priming pump

A hand pump is installed in the upper part of the filter housing (in older models with a Bosch injection system). The pump can be used to bleed and remove air from the system. Self-bleeding occurs when the starter is pressed in new models. For this reason, hand pumps were no longer installed in newer models.

Note: There is another fuel filter located inside the fuel tank. If the fuel system does not provide enough fuel, this filter is likely dirty. The filter can be accessed by removing the fuel tank sender.

Removal water from the fuel filter

Water should be removed from the fuel filter regularly. It has already been said why this is necessary.

Place a container under the vehicle to collect the drained diesel fuel.

Unscrew the air bleed plug.

Loosen the water drain plug. Let the water drain until clean fuel appears.

Tighten the cap.

Bleed the system with a hand pump or, in the case of a vehicular pump, start the engine for automatic bleeding.

Replacing the filter element

a) For the Bosch fuel pump:

• Unscrew the entire bottom part of the filter.
• To do this, place a wrench on the Allen key at the bottom of the filter (above the screw plug).
• Replace the filter element with a new one.
• Bleed the system manually or with the engine running.

b) For models with fuel pump "Lucas-CAV":

• Loosen the mounting bolt in the middle of the filter housing from the top until it rotates easily.
• Release the filter from its mounting on the body.
• The filter element should be replaced with a new one.
• When assembling the housing, keep in mind that the filter element must be exactly in the middle, it presses on the sealing ring at the top and bottom of the filter.
• Install the filter on the body, tighten the central bolt.

The picture shows a fuel filter of the "Lucas-CAV" model. The upper arrow points to the air bleed plug; the bottom one is on the plug for removing water.

Bosch fuel filter without hand pump: 1 - fuel line leading to the high-pressure fuel pump; 2 - fuel line coming from the tank; 3 - air release plug; 4 - removable part of the filter; 5 - water drain plug.