3.0L V6 (Engine Code: Avk): Diagnosis Audi A6 C5 facelift

Test sequence

1. Remove connecting rod bearing caps. Clean bearing caps and journals.
2. Place Plastigage over entire width of bearing journal or into bearing shells.
3. Install connecting rod bearing caps and tighten to 30 Nm. DO NOT turn the crankshaft.
4. Remove connecting rod bearing caps again.
5. Compare width of Plastigage with calibrated scale.

CONNECTING ROD RADIAL PLAY (BEARING CLEARANCE) SPECIFICATIONS

Note. Always replace connecting rod bolts.

Test requirements

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

1. Remove rear engine cover (arrows).
2. Remove cover -1- in engine compartment (left side).
3. Remove coolant reservoir (arrows).
4. Disconnect electrical wiring to Engine Coolant Level (ECL) Warning Switch -F66- at bottom of expansion tank.
5. Tie coolant expansion tank with connected coolant hoses -1 to 3- to side.
6. Remove cover -1- in engine compartment (right side).
7. Remove bolts (arrows).
8. Remove air guide -1-.
9. Disconnect Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80- -1- at air filter housing.
10. Disconnect electrical harness connector -2- at Mass Air Flow (MAF) sensor.
11. Remove air guide hose -3- together with Mass Air Flow (MAF) sensor.
12. Remove air filter housing (arrows).
13. Remove bolts -4- and -5- from left cylinder head. see scheme 275
14. Disconnect electrical harness connectors -1- to -3- and -6-.
15. Remove ignition coils (arrows).
16. Remove bolts -5- and -6- from right cylinder head. see scheme 276
17. Disconnect electrical harness connectors -1- to -4-.
18. Remove ignition coils (arrows).
19. Using 3122B spark plug removal tool, remove spark plugs.
20. Remove all harness connectors to injectors.
21. Open throttle fully.
22. Using VAG1381 or VAG1763 compression tester, test engine compression.

Note. Using VAG1381 or VAG1763 Compression Tester

See Operating instructions

1. Activate starter until no further pressure increases are indicated by VAG1381 or VAG1763 compression tester.

Compression values

ENGINE COMPRESSION VALUES (BAR)

1. Install spark plugs and ignition coils.

The following work step must be performed after the engine compression test.

1. Checking DTC and erasing if necessary.

Use VAS5051 tester to do so.

1. Remove camshafts. See «CAMSHAFTS AND CAMSHAFT ADJUSTERS, REMOVING AND INSTALLING»(ref-196254-S11217339502005100700000) .
2. Remove hydraulic valve lifters.
3. Insert camshafts into cylinder head and install guide frame.
4. Secure VW387 dial gauge holder with dial indicator to cylinder head.
5. Press camshaft to be checked against dial indicator by hand.
6. Set dial indicator to -0-.
7. Press crankshaft away from dial indicator.
8. Read clearance.

Scheme 333

CAMSHAFT AXIAL PLAY SPECIFICATIONS

Note. Hydraulic valve lifters cannot be serviced. Irregular valve noise when starting engine is normal.

1. Start engine and let run until coolant temperature reaches at least 80° C.
2. Increase RPM to 2500 for approx. 2 minutes, if necessary road test vehicle.

Note. If unusual valve noises disappear but then reappear during drive, replace oil retaining valve. Oil retaining valve, component location: Below cover at intake manifold, see OIL CHECK VALVES AND SPRAY JET VALVE, OVERVIEW .

If hydraulic valve lifters are still loud, locate faulty valve lifter as follows

1. Remove cylinder head cover, see «LEFT CYLINDER HEAD COVER, REMOVING AND INSTALLING»(ref-196254-S30023212172005100700000) or «RIGHT CYLINDER HEAD COVER, REMOVING AND INSTALLING»(ref-196254-S04705591322005100700000) .
2. For vehicles with auxiliary heater, remove bolts (arrows) for exhaust pipe of parking heater/auxiliary heater at noise insulation.
3. Loosen mounting parts -1 to 4- and remove noise insulation.
4. Turn crankshaft at center bolt of toothed belt gear clockwise until cams of cylinder to be checked point upward -arrows-.
5. Determine play between cams and valve lifters.
6. Press valve lifter downward using wooden or plastic wedge. If 0.20 mm feeler gauge can be inserted between camshaft and valve lifter, replace valve lifter.

Valve lifters, replacing, and removing camshafts, see CAMSHAFTS AND CAMSHAFT ADJUSTERS, REMOVING AND INSTALLING .

Scheme 334

Note. After installing camshafts, do not start engine for at least 30 minutes. The hydraulic valve lifters have to settle (otherwise valves will strike the pistons). After working on the valvetrain, carefully rotate engine by hand at least 2 full revolutions to ensure that valves do not strike the pistons when starting.

1. VAS5051 tester connected and vehicle On Board Diagnostic (OBD) -01, Engine electronics-selected.
2. Coolant Temperature at least 80°C.
3. Vehicles with automatic transmission Selector lever in P or N.

1. Start engine, and let run at idle.

Display on VAS5051

Scheme 335

1. In selection -1-, click on the diagnostic function "04 - Basic setting".

Display on VAS5051

1. Enter display group max. input value = 255

1. Select function "094" in button field -2- for "display group number 094" and press Q button to confirm input.

Scheme 336

Display on VAS5051

1. Activate basic setting by pressing button A.
2. Depress accelerator pedal and brake pedal at the same time, engine speed increases to approx. 1900 RPM.

Test requirement

1. Accelerator pedal and brake pedal depressed at the same time, engine runs at approx. 1900 RPM.

Scheme 337

1. Check specified values in display fields -3- and -4-.
2. Click on - button

Display on VAS5051

1. Enter display group max. input value = 255

1. Select function "096" in button field -2- for "display group number 096" and press Q button to confirm input.

Indicated on display of VAS 5051

1. Activate basic setting by pressing button A.
2. Depress accelerator pedal and brake pedal at the same time, engine speed increases to approx. 1900 RPM.

1. Accelerator pedal and brake pedal depressed at the same time, engine runs at approx. 1900 RPM.

1. Check specified values in display fields -3- and -4-.
2. Click on - button.
3. Switch over to Read measured value block.

1. Engine running at idle.

1. Check specified values in display fields -2-, -3- and -4-.
2. Perform a road test.
3. Accelerate vehicle in 3rd gear at full throttle from 2000 RPM.
4. Check specified values in display fields -2-, -3- and -4-.

Scheme 338

Note. If display field indicates a value between 3.0° crankshaft rotation and 19.0° crankshaft rotation during a road test, the electrical valve for camshaft adjustment is correctly switching the oil pressure to mechanical camshaft adjuster, but the mechanical camshaft adjuster cannot reach its end position (e.g. due to difficulty of movement).

Scheme 339

1. Engine running at idle.

1. Check specified values in display fields -3- and -4-.
2. Perform a road test.
3. Accelerate vehicle in 3rd gear at full throttle from 2000 RPM.
4. Check specified values in display fields -3- and -4-.

Scheme 340

Note. If display field only indicates a value between 3.0° crankshaft rotation and 39.0° crankshaft rotation during a road test, the electrical valve for camshaft adjustment is correctly switching the oil pressure to mechanical camshaft adjuster, but the mechanical camshaft adjuster cannot reach its end position (e.g. due to difficulty of movement).

Indicated on display of VAS 5051

1. Press s -button to change into display group 092.

1. Engine running at idle.

Scheme 341

Scheme 342

1. Check specified values in display fields -3- and -4-.
2. Perform a road test.
3. Accelerate vehicle in 3rd gear at full throttle from 2000 RPM.
4. Check specified values in display fields -3- and -4-.

Scheme 343

Note. If display field only indicates a value between 3.0° crankshaft rotation and 39.0° crankshaft rotation during a road test, the electrical valve for camshaft adjustment is correctly switching the oil pressure to mechanical camshaft adjuster, but the mechanical camshaft adjuster cannot reach its end position (e.g. due to difficulty of movement).

1. VAS5051 tester connected and vehicle On Board Diagnostic (OBD) -01 Engine electronics-selected.

1. Oil level OK
2. Engine oil temperature approx. 80° C.
3. With ignition on, Oil Pressure Warning Light -K3 must be lit.
4. For vehicles with Auto Check System, "OK" indicator must be lit (call up symbol).