Audi Workshop Service and Repair Manuals

Checking compression

Special tools and workshop equipment required

t	Spark plug socket and extension -3122 B-

t	Compression tester -V.A.G 1763-

t	Puller -T40039-

Procedure l  Engine oil temperature min. 30 °C. l  Battery voltage at least 12.5 V –  Pull off rear engine cover panel -top arrows-.

–  Remove bolts -arrows-. –  Unplug electrical connector at coolant shortage indicator switch -F66- and move expansion tank to one side with coolant hoses -1, 2, 3- attached.

–  Remove bolts -arrows- and unplug electrical connectors at ignition coils on cylinder head (left-side). –  Press electrical wiring harness down slightly.

–  Unplug electrical connector -3- for injectors at rear of cylinder head (left-side).   Note Disregard items marked -1, 2, 4- and -arrows-.

–  Remove air duct -arrow-.

–  Move fuel line -1- and line -2- (leading to activated charcoal filter) clear at air pipe. –  Disconnect vacuum hose -3- from connection on air pipe. –  Remove air pipe. To do so, release hose clip -4- and clamps -arrows-.

–  Disconnect vacuum line -1-. –  Detach air cleaner housing and, if fitted, unplug electrical connector -2- at variable intake manifold change-over valve -N335- on reverse side of air cleaner.

–  Remove bolts -arrows- and unplug electrical connectors at ignition coils on cylinder head (right-side). –  Move wiring harness clear to the side.

–  Unplug electrical connector -3- for injectors at rear of cylinder head (right-side).   Note Disregard items marked -1, 2, 4- and -arrows-.

–  Remove all ignition coils using puller -T40039-. –  Remove spark plugs with spark plug socket and extension -3122 B-. –  Check compression pressure with compression tester -V.A.G 1763-.   Note Using the compression tester → Operating instructions. –  Have a 2nd mechanic press down the accelerator pedal completely and at the same time operate the starter until the pressure on the tester display no longer increases.

Compression pressure	bar
When new	10.0 … 14.0
Wear limit	9.0
Maximum difference between cylinders	3.0

Assembling l  Tightening torque → Chapter. Installation is carried out in the reverse order; note the following:   Note Secure all hose connections with the correct type of hose clips (same as original equipment) → Electronic parts catalogue. –  Install spark plugs → Booklet811, → Booklet812 or → Booklet818. –  Install air cleaner housing → Rep. Gr.24. –  Faults are stored in engine control unit because electrical connectors were unplugged and engine was started: “Generate readiness code” in “Guided Functions” → Vehicle diagnosis, testing and information system VAS 5051.