Water Pump: Service and Repair

Coolant Pump (V50)

• Coolant Pump (V50) is currently not installed on all vehicles; for vehicles with a 6 cylinder gasoline engine, coolant pump is installed only on vehicles with parking heater optional equipment.

• The coolant pump is actuated independent of vehicle equipment by the respective Engine Control Module (ECM) and by the Climatronic Control Module (J255) (for example, via Coolant Circulation Pump Relay (J151) ). Refer to and Vehicle Diagnosis, Testing and Information System VAS5051 in the "Guided Fault Finding" function.

• On vehicles with 6 cylinder gasoline engine without parking heater optional equipment, the Coolant Pump (V36) is installed in place of Coolant Pump (V50) , it is actuated via, for example, Recirculation Pump Relay (J160). Refer to and Vehicle Diagnosis, Testing and Information System VAS5051 in the "Guided Fault Finding" function.

For a complaint of poor heating performance, check before removing Coolant Pump (V50) ( Coolant Pump (V36) )

- Incorporation into coolant circuit (correct connection of coolant hoses at supply and return to engine), refer to => [ Incorporation of Front HVAC System into Cooling Circuit ] Incorporation of Front HVAC System Into Cooling Circuit.

- Actuation of Coolant Pump (V50) (of Coolant Pump (V36) ) by the Climatronic Control Module via the respective relay, refer to and Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function.

- Bleed coolant circuit again, observe the notes for this as well while doing this, refer to => [ Coolant System, Bleeding ] Coolant System, Bleeding.

- On certain vehicles with a 6 cylinder TDI engine without an auxiliary heater but with an Auxiliary heater heating element (Z35) installed due to a specific Emission Standard, check the function and activation of the auxiliary heater heating element, refer to => [ Auxiliary Heater Heating Element, Checking ] Testing and Inspection.

• If the coolant pump causes noise, check the bleeding of the coolant circuit, refer to => [ Coolant System, Bleeding ] Coolant System, Bleeding before removing.

Special tools, testers and auxiliary items required

• Hose Clamps Up To Diameter 25 mm (3094)

• Cooling System Tester (V.A.G 1274) (hand pump and corresponding adapter)

Removing

- Switch off ignition.

- Remove left front wheel.

- Remove left front wheel housing liner..

- Dissipate pressure in coolant circuit by opening cap at coolant expansion tank.

- Loosen pipe group with coolant pump - E - from vehicle.






- Mark the arrangement of coolant hoses - D - (supply to heater core) and - C - (supply to engine).

- Clamp off coolant hose to heater core - B - (for example, using (3094) ).

- Disconnect connector - A - from coolant pump.

- Remove bolts - F - and - G -.

- Clamp off coolant hose (from engine) - C - (for example, using (3094) ).

• If coolant hose - C - (different versions) should be too short to clamp, seal it for example, using a sealing plug after disconnecting.

- Disconnect coolant hoses - C - and - D - from coolant pump.

- Remove coolant pump - E -.

Installing

Installation is carried out in the reverse order while noting the following:

• With a discharged coolant circuit, a new coolant pump - E - must only be brought into operation only after the coolant circuit has been charged, dry-running a pump may destroy it.

• Since only a small amount of coolant flowed out of coolant circuit when removing coolant pump - E - as described above, coolant flows immediately into coolant pump after installing and removing the hose clamps and there is no danger of dry-running the pump.

- Connect 2-pin harness connector - A - to pump only after removing the hose clamps.

- Re-install the remaining removed components.

- Bleed coolant circuit, refer to => [ Coolant System, Bleeding ] Coolant System, Bleeding.

- Add coolant if necessary.