Removing and installing coolant shut-off valve -N279 — AUDI

Notes:

If voltage is not applied to coolant shut-off valve -N279 (large coolant circuit), coolant can flow from connection -B- (from pump/valve unit) to connection -A- (to engine).
If voltage is applied to coolant shut-off valve -N279 (small coolant circuit), coolant can flow from connection -B- (from pump/valve unit) to connection -C- (to auxiliary heater).
If coolant shut-off valve is replaced, coolant hoses may also have to be replaced due to different connection diameters depending on manufacturer (Bosch or Woco). Only Woco shut-off valves are available as replacement parts.
Connection -D- (or -C-) is sealed with a plug (depending on installation position).
Depending on design of -N279, connections of shut-off valve are marked with numbers and arrows ("1" = -A-, "2" = -C-, "3" = -B- and "4" = -D-).

Fitting location on vehicles with 8-cyl. 4-valve petrol engine (retrofitted) =>Page
82-243
Coolant shut-off valve -N279 is actuated by relay -J541 in auxiliary heating mode=>Page
01-205
.

Special tools, testers and other items required

Hose clamps 3093/3094

Removing

Notes:

On removal, note down bolt lengths and assignment for re-installation.
All cable ties and other wiring harness fasteners released or cut open on removal are to be re-attached in same position on installation.

Switch off ignition.
Dissipate pressure in coolant circuit by opening cap at coolant expansion tank.

=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
Relevant Engine, Mechanics Workshop Manual

Removal on vehicles with 8-cyl. petrol engine

Unplug connector -A-.
Mark positions of coolant hoses -B-, -C- and -D-.
Pinch off coolant hoses to coolant shut-off valve -N279 (e.g. using V.A.G 3094) and detach hoses.
Remove bolts -E-.
Remove shut-off valve -F-.

Removal on vehicles with 12-cyl. engine

Remove air cleaner assembly.

=> Relevant Engine, Mechanics Workshop Manual

Remove front right wheel housing liner.

=> General Body Repairs; Repair Group 63
General Body Repairs

Unplug connector -A-.
Mark positions of coolant hoses -B-, -C- and -D-.
Pinch off coolant hoses to coolant shut-off valve -N279 (e.g. using V.A.G 3094) and detach hoses.
Remove bolts -E-.
Remove shut-off valve -F-.

Installing

Re-install components removed in reverse order.
Bleed coolant circuit =>Page
82-133
and

=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
Relevant Engine, Mechanics Workshop Manual

If necessary, check operation of shut-off valve =>Page
01-205
.