Compression Check: Testing and Inspection

Compression Checking

• With this engine, the static compression test requires a significant amount of work. Therefore it is recommended to check idle stabilization control before disassembly. Refer to or VAS 5052 "Guided Fault Finding; Repair Group 15; partial systems, boundary conditions". Only if one or more cylinder(s) is/are noticeable at this point is the compression test warranted.

Special tools, testers and auxiliary items required

• Torque wrench (5 to 50 Nm) (VAG 1331)

• Adapter (VAG 1381/12)

• Compression tester (VAG 1763)

Test conditions

• Engine oil temperature min. 30 °C

• Ignition switched off

Test Sequence

- Drain the cooling system. Refer to --> [ Cooling System, Draining and Filling ] [1][2][3]Cooling System, Draining and Filling.

With engine code BKW

- Remove fuel filter. Refer to --> [ Fuel Filter ] .

- Seal connection for fuel hoses using sealing plate (T10247).





- Connect fuel supply line - A - using connecting hose (VAS 6278) to fuel return line - B -.





With Engine Code BWF

- Remove bypass flap with cooler for Exhaust Gas Recirculation (EGR). Refer to --> [ Bypass Flap with Cooler Assembly Overview ] Bypass Flap with Cooler Assembly Overview.

Continuation for All

- Remove the upper part of oil filter housing. Refer to --> [ Oil Filter Housing Assembly Overview ] Oil Filter Housing Assembly Overview.

- Remove the glow plugs. Refer to --> [ Ceramic Sheathed Element Glow Plugs ] Service and Repair.

- Remove right plenum chamber cover - D -.





- Disconnect small connectors from Engine Control Modules (ECM).

• By disconnecting the small harness connectors for ECM the engine is prevented from starting up even though the starter is turning. If any Diagnostic Trouble Codes (DTCs) are stored in DTC memory during start procedure, it is necessary to check and erase (if required) the DTC memory.

• After the compression test, check the DTC memory. Refer to --> [ Engine Control Module, DTC Memory Checking and Erasing ] Component Tests and General Diagnostics.

- Install adapter (VAG 1381/12) in place of glow plug at cylinder to be tested.





- Reinstall the upper part of oil filter housing. Refer to --> [ Oil Filter Housing Assembly Overview ] Oil Filter Housing Assembly Overview.

- Check compression pressure using the compression tester (VAG 1763).

• Using the compression tester, refer to --> Operating instructions.

- Operate starter until tester shows no further pressure increase.

Compression Pressure

• New: 25 to 0.31 bar pressure

• Wear limit: 19 bar pressure

• Permissible difference between all cylinders: 5 bar

- Install the glow plugs. Refer to --> [ Ceramic Sheathed Element Glow Plugs ] Service and Repair.

- Fill the cooling system. Refer to --> [ Cooling System, Draining and Filling ] [1][2][3]Cooling System, Draining and Filling.

- After all cylinders have been checked and engine has been completely reassembled, check DTC memory and erase it if necessary. Refer to --> [ Engine Control Module, DTC Memory Checking and Erasing ] Component Tests and General Diagnostics.