Audi Workshop Service and Repair Manuals

Removing and installing thermostat

Special tools and workshop equipment required

t	Locking pin -T40011-

t	Socket (22 mm) -3078-

t	Locking pin -3242-

t	Diesel injection pump locking pin -3359-

t	Locking fluid → Electronic parts catalogue

Removing l  Lock carrier must be in service position → Chapter. –  Remove poly V-belt for power steering pump, alternator and viscous fan → Chapter. –  Remove securing bolts -arrows- for toothed belt cover (rear right). –  Drain coolant → Chapter.

–  Open oil filler cap. –  Turn engine until the marking “- OT -” (TDC) is visible on camshaft.   Caution The engine must only be turned at the crankshaft, in the direction of normal engine rotation (clockwise).   Note Turn over the engine at the central bolt on the crankshaft.

–  Unscrew plug for TDC marking from cylinder block.   Note There is a TDC drilling in the crankshaft directly behind the plug (it is possible to feel the hole).   WARNING Injury risk. Do not rotate the crankshaft while feeling for the TDC drilling with your finger. –  Screw locking pin -3242- into threaded hole where plug has been removed, and tighten.

–  Remove vibration damper on injection pump sprocket (bolts -1-).   Caution Do NOT loosen nut -2- for injection pump sprocket. Otherwise this would alter the basic setting of the injection pump. The setting cannot be re-adjusted with workshop equipment.

Caution If a used belt runs in the opposite direction when it is refitted, this can cause breakage. Before removing, mark direction of rotation of toothed belt with chalk or felt-tipped pen for re-installation. –  Slacken toothed belt tensioner and take off toothed belt for injection pump.

–  Remove 8 bolts -1- and detach vibration damper.   Note Central bolt does not have to be loosened when removing vibration damper.

–  Unbolt bottom section of toothed belt cover -4-. –  Unbolt viscous fan pulley. –  Remove bolts -1 ... 3- and detach bracket for viscous fan with idler rollers.

–  Unbolt drive sprocket -1- for injection pump from camshaft sprocket -arrows-.   Note Do not use camshaft holders -3458- as counterhold tools.

–  Turn toothed belt tensioning roller in clockwise direction -arrow- using an 8 mm hexagon key until tensioning lever of tensioner is compressed far enough to allow locking pin -T40011- to be inserted into hole and plunger.   Note The toothed belt tensioner is oil-damped and can therefore only be compressed slowly by applying constant pressure.

–  Pull toothed belt forwards slightly on tensioning roller -arrow-.   Caution Timing must be re-adjusted if toothed belt has slipped off tensioning roller → Anchor. –  Detach coolant hose from thermostat housing. –  Remove bolts -1 ... 3- and detach thermostat housing. –  Remove O-ring and thermostat.

Installing Installation is carried out in the reverse order; note the following:   Note Renew seals and O-rings. –  Install thermostat (note installation position): l  Vent valve -arrow- faces upwards. l  O-ring faces towards housing. –  Install thermostat housing.

–  Apply locking fluid to bolts -2- and -3- before installing.   Caution Timing must be re-adjusted if toothed belt has slipped off tensioning roller → Anchor. –  Push toothed belt to rear.

–  Use an 8 mm hexagon key to slacken toothed belt tensioning roller in clockwise direction -arrow- and pull out locking pin -T40011-.

–  Use torque wrench to pretension toothed belt to 15 Nm in anti-clockwise direction -arrow-.

–  Tighten bolts for bracket for viscous fan: 1 -  45 Nm 2 -  10 Nm 3 -  22 Nm 4 -  10 Nm

–  Lock injection pump sprocket with diesel injection pump locking pin -3359-.

–  Fit drive sprocket for injection pump -1- so that it is aligned centrally in elongated holes. –  Tighten drive sprocket -arrows- until it is still just possible to turn it on the camshaft sprocket. –  Position toothed belt for injection pump. Pay attention to the direction of rotation as marked upon removal.

–  Tension toothed belt by turning Allen key in anti-clockwise direction -arrow- until marks -1- coincide. –  Then tighten nut using socket (22 mm) -3078-.   Note Depending on version, pointer -1- may have no tip. –  Tighten bolts at camshaft sprocket. –  Remove diesel injection pump locking pin -3359-. –  Remove locking pin -3242-. –  Screw plug for the TDC mark into cylinder block with a new seal.

–  Check tension of toothed belt for injection pump. l  Marks -1- and -2- must be opposite one another.

–  Fit vibration damper on injection pump sprocket (bolts -1-).

–  Install vibration damper. In doing so, pay attention to locking lug -arrow- on toothed belt sprocket. Remaining installation steps are carried out in reverse sequence; note the following: –  Install poly V-belt for power steering pump, alternator and viscous fan → Chapter. –  Fill up with coolant → Anchor. –  Dynamically check and adjust commencement of injection → Rep. Gr.23. Tightening torques

Component	Nm
Vibration damper to injection pump sprocket	22
Drive sprocket for injection pump to camshaft	22
Vibration damper to crankshaft sprocket	22
Screw plug in cylinder block	10
Tensioning roller for injection-pump toothed belt to bracket for viscous fan	36
Viscous fan pulley to hub	10
Viscous fan to bearing	70