Compression, Checking

The compression can be checked with the following testers.

• Vehicle Diagnostic Tester
• Compression Tester Kit: V.A.G 1763 
• Pressure-Loss Tester: VAS 522 001 
• CO2 Coolant Tester: VAS 531 009 

Procedure using Vehicle Diagnostic Tester:

Special tools and workshop equipment required 

• Vehicle Diagnostic Tester

-- Connect the Vehicle Diagnostic Tester.

-- Switch the ignition on.

-- Select the engine electronics  .

-- Select subsystem - constraints  .

-- Select compression test  from the list.

If a cylinder is noticeable, check the compression using the Compression Tester Kit: V.A.G 1763  .

Procedure using the Compression Tester Kit: V.A.G 1763  :

Special tools and workshop equipment required 

• Compression Tester Kit: V.A.G 1763  with Compression Tester Kit - Adapter 8: V.A.G 1763/8 
  Fig 1: Compression Tester Kit VAG 1763

  Courtesy of AUDI OF AMERICA, LLC

• Engine oil temperature at least 30 °C.
• Battery voltage at least 12.5 V.

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

-- Disconnect the connector on the Fuel Pressure Regulator Valve -N276- -2-.

-- In order to reduce the fuel pressure in the high pressure reservoir, start the engine briefly.

-- Remove all glow plugs. Refer to GLOW PLUG, REMOVING AND INSTALLING .

-- Install the Compression Tester Kit - Adapter 8: V.A.G 1763/8  in place of the glow plug and connect the Compression Tester Kit: V.A.G 1763  .

-- 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	25.0 to 31.0
Wear limit	19.0
Maximum difference between cylinders	5.0

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 

Assemble in the reverse order of removal. Note the following:

-- Install all glow plugs. Refer to GLOW PLUG, REMOVING AND INSTALLING .

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

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