Audi Workshop Service and Repair Manuals > A3 Mk2 > Power unit | 4-cylinder TDI unit injector engine (1.9 ltr.; 2.0 ltr. 2-valve), mechanics | Exhaust turbocharger, G-charger | Turbocharger and charge air cooler

Checking charge air system for leaks

Special tools and workshop equipment required

t	Charge air system tester -V.A.G 1687- with adapter -V.A.G 1687/12-

Procedure

–	Remove centre noise insulation -fasteners 1 ... 3-.

–	Detach air intake hose (left-side) from air pipe (lift retaining clip -right arrow- slightly).

–	Fit adapter -V.A.G 1687/5- onto charge air hose -A- and turn by approx. 90° -B-.

–	Connect charge air system tester -V.A.G 1687- to adapter.

Prepare charge air system tester -V.A.G 1687- as follows:

–	Unscrew pressure control valve -2- completely and close valves -3- and -4-.

l	Make sure knob is pulled out before turning pressure control valve -2-.

–	Using a commercially available connection piece, connect charge air system tester -V.A.G 1687- to compressed air -1-.

Note

If there is water in sight glass, remove drain plug -6- and drain water.

–	Open valve -3-.

Caution

Risk of damage if pressure is set too high.

The pressure must not exceed 0.5 bar.

–	Adjust pressure to 0.5 bar via pressure control valve -2-.

–	Open valve -4- and wait until test system is pressurised. If necessary, adjust pressure to 0.5 bar again.

–	Check charge air system for audible leaks or leaks that can be felt with the hand; apply commercially available leak detecting spray or use ultrasonic tester -V.A.G 1842-.

Note

t	A small amount of air escapes through the valves and enters the engine. Therefore it is not possible to perform a pressure retention test.

t	For operation of ultrasonic tester -V.A.G 1842-, refer to → Operating instructions.

t	Release pressure in test circuit by detaching hose coupling from adapter before removing adapter.

t	Hose connections and air pipes and hoses must be free of oil and grease before assembly.

t	Secure all hose connections with the correct type of hose clips (same as original equipment) → Electronic parts catalogue.

t	To ensure that the air hoses can be properly secured at their connections, spray rust remover onto the worm thread of used hose clips before installing.

Audi Workshop Service and Repair Manuals