Compression, Checking

WARNING: This page is about a different car, the 2024 Audi A3 Quattro and 2024 Audi A3. However, it is still accessible from the selected car via links, so may be relevant.

Special tools and workshop equipment required

Spark Plug Removal Tool:3122 B

Fig 1: Identifying Spark Plug Removal Tool 3122B
Courtesy of AUDI OF AMERICA, LLC
Compression Tester Kit:V.A.G 1763

Fig 2: Compression Tester Kit VAG 1763
Courtesy of AUDI OF AMERICA, LLC
Adapter:V.A.G 1763/13 , not illustrated

Test Sequence

Engine oil temperature at least 30 °C.
Battery voltage at least 12.7 V.

-- Remove the engine cover. Refer to ENGINE COVER, REMOVING AND INSTALLING .

-- Disconnect the fuel injector connector -arrow-.

Courtesy of AUDI OF AMERICA, LLC

-- Remove the ignition coils. Refer to IGNITION COILS, REMOVING AND INSTALLING .

-- Remove the spark plugs using the Spark Plug Removal Tool:3122 B .

Courtesy of AUDI OF AMERICA, LLC

-- Install the Adapter:V.A.G 1763/13 as shown in the respective spark plug hole and connect the Compression Tester Kit:V.A.G 1763 .

Courtesy of AUDI OF AMERICA, LLC

-- Check the compression using the Compression Tester Kit:V.A.G 1763 . Refer to the Operating Manual.

-- Have a second technician operate the starter until the tester stops displaying a pressure increase.

-- Repeat the procedure on each cylinder.

Compression pressure	bar pressure
New	16.0 to 19.0
Wear limit	12.0
Maximum difference between cylinders	3.0

TIP:

If the test with the Compression Tester Kit:V.A.G 1763 does not lead to a clear result there are two additional tests.

In addition to the compression test a pressure test can be performed with the Pressure-Loss Tester:VAS 522 001 . The procedure for this is described in the operating instructions for the Pressure-Loss Tester:VAS 522 001 .
As an additional test the CO2 content in the coolant expansion tank can be measured. A raised CO2 content in the cooling system indicates a leak between the combustion chamber and the cooling system. The CO2 content can be determined using the CO2 Coolant Tester:VAS 531 009 . The procedure for this is described in the operating instructions of the CO2 Coolant Tester:VAS 531 009 .

Assembling

-- Install the spark plugs. Refer to OVERVIEW - IGNITION SYSTEM .

-- Install the ignition coils. Refer to IGNITION COILS, REMOVING AND INSTALLING .

-- Install the engine cover. Refer to ENGINE COVER, REMOVING AND INSTALLING .

-- Delete the DTC memory entries in the engine control module that have occurred during the test using the Vehicle Diagnostic Tool.