Compression, Checking

Special tools and workshop equipment required 

• Compression Tester Kit:V.A.G 1763 
  Fig 1: Compression Tester Kit VAG 1763

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• Spark Plug Socket Adapter 3/8" :VAS 6919  , not illustrated

Procedure

• The engine oil temperature must be at least 30 °C
• Battery voltage at least 12.5 V.

-- Remove the fuse for the Fuel Pump Control Module -J538-. Refer to the appropriate Wiring Diagram.

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

-- Remove the spark plugs using the Spark Plug Socket Adapter 3/8":VAS 6919  .

With Compression Tester Kit - Adapter:V.A.G 1763/12  :

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-- Install the Compression Tester Kit:V.A.G 1763  as shown in the corresponding spark plug connectors.

With Compression Tester Kit - Adapter:V.A.G 1763/12A  :

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-- Install the Compression Tester Kit:V.A.G 1763  as shown in the corresponding spark plug connectors.

Continuation:

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

• The help of a second technician is necessary for the following step.

-- 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	10.5 to 15.5
Wear limit	8.5
Maximum difference between cylinders	3

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 internal combustion engine 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  .

Assemble in the reverse order of removal.

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

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

-- Install the fuse for the Fuel Pump Control Module -J538-. Refer to the appropriate Wiring Diagram.

-- Delete DTC entries which were generated during testing using the Vehicle Diagnostic Tester.