Heater Core: Service and Repair

Heater Core

Special tools, testers and auxiliary items required

• drip tray for shop crane (VAS 6208)

• Hose clamps up to dia. 40 mm (VAS 3093)

• Compressed air gun, commercially available

Removing

- Place the drip tray for shop crane (VAS 6208) under the motor.

CAUTION!
Contact with hot engine coolant can cause severe scalding.

Coolant temperature can be above 100 ? with a warm engine. The cooling system is under pressure.

If necessary, reduce pressure and temperature before repairs.

- Clamp off coolant hoses - 1 - using hose clamps up to dia. 40 mm (VAS 3093) and disconnect coolant hoses to heater core.





- Connect a section of hose - A - onto upper connection of heater core.

- Hold a container - B - under the lower connection - C -.





- Using a compressed air gun, carefully blow coolant out of heater core into container - B -.





- Slightly loosen (do not remove) screw (6 mm hex socket head) - 1 - on connecting flange between heater core connections.

• This allows the coolant pipes to move for removing the heater core.

- Remove driver side footwell trim.

- Remove left footwell vent. Refer to => [ Left Footwell Vent ] Removal and Replacement.

- Remove screws - 1 - and remove heater core trim.





- Cover floor carpet in area below heater core with leak-proof foil and absorbent paper.

- Open hose clamps - A - and disconnect coolant pipes from heater core.





- Remove heater core from heating unit.

Installing

Installation is carried out in the reverse order, when doing this note the following:





- Check seals - A - and - B - installed on heater core, only install a heater core with undamaged seals.

• An incorrectly glued seal can roll up into heating unit when sliding in the heater core.

• Cold air may flow past heat exchanger if seal is damaged or not properly fitted.

- With the heater core removed, check heating unit for soiling (via heater core opening - A -).





- If necessary remove dirt or coolant from heating unit, for example after removing leaky heater core.

- Push heater core into heating unit.

- The sealing rings - 1 - must be replaced.





- Coat the sealing rings with coolant before installing

• If hose clamps are deformed, replace them.

- Connect coolant pipes to heater core.

- Hose clamps - A - must be able to be twisted slightly when installing onto the coolant pipes.





- Hose clamps - A - must be installed as shown in the illustration.

- Tighten hose clamps - A - to 2.0 Nm.

- Check seating of both clamps - A - after tightening bolts, clamps must enclose the flange on heater core and coolant pipe completely and must not touch other components.





- Tighten the screw - 1 - from the connecting flange between heater core connections to 2 Nm.

- Check position of grommet - C - in bulkhead for proper seating.





- Seal the flange for coolant pipes to heater core - A - and for expansion valve (to evaporator, only in vehicles with A/C system) - B - at pass-throughs of grommet - C - with silicon adhesive sealant if necessary (to prevent water from penetrating).

• Sealing rings must always be replaced.

• If hose clamps are deformed, replace them.

• After replacing heater core, coolant must be replaced completely.

• Check coolant circuit for leaks, pay particular attention between coolant hoses and heater core.