Problem description

Timing chain problems, including stretched timing chain, malfunctioning timing chain tensioner and rattling noises from the timing chain housing have been repeatedly reported for the VAG TSI 2.0 liter turbocharged engine family. In some cases, a stretched chain can throw camshaft timing off. In extreme cases, the chain can break leading to catastrophic engine failure.

If the engine is running rough and the MIL is illuminated, get preliminary diagnosis using a scan tool plugged into the OBD II outlet underneath the dashboard. Monitor the ECM / live data. Use data block (MVB) 91. With the engine at idle, intake camshaft adjustment specified and actual should be within +5 degrees or -5 degrees. Any larger value indicates a timing chain that is dangerously stretched.

Additional confirmation

• Remove upper timing cover.
• Rotate engine until camshaft timing marks on sprockets point up.
• Measure distance between camshaft timing marks.
• The correct distance between marks is 124 – 126 mm.
• The distance specification from intake camshaft to the mark on the cam cover is 61 – 64 mm.

If timing is off, the timing chain is stretched and should be replaced. In addition:

• If timing is off by as much as one whole sprocket tooth, it indicates that the chain jumped timing and may have caused valve / piston interference. Additional testing for internal engine damage is required.
• Inspect for the oil screen located in the camshaft adjuster bridge. It may have come apart and lodged itself within the camshaft adjuster spool and the intake camshaft adjuster (only serviced with the intake camshaft).

Repairs

Check-valve oil screen problems

If timing specifications (as read using scan tool) exceeds ±5°, but distance measurement between timing marks is correct (124 – 126 mm), check that the oil screen in the camshaft adjuster bridge is still in place.

If oil screen has come apart and lodged itself within the camshaft adjuster spool and intake camshaft adjuster:

• Remove camshaft bearing bracket.
• Check non-return check-valve in bearing bracket.
• Check camshaft bearing journals and camshafts. If scoring can be felt on journals or camshafts, replace bearing bracket and camshaft.
• Remove camshaft sprockets and use pressurized oil to test non-return oil check-valve in cylinder head. Apply 0.5 bar pressure and make sure pressure does not drop or leak away within 1 minute.
• If cylinder head check-valve is leaky, remove cylinder head and replace check-valve.

In case of torn oil screen:

• If strainer is metal, reuse camshaft bearing bracket using a new check-valve.
• If strainer is plastic, replace camshaft bearing bracket.

Make sure remnants of strainer are removed from oil duct. Remnants can clog up oil duct in camshaft bearing bracket or drift into camshaft bearing. This can damage other components. Check camshaft adjuster for debris and thoroughly clean if necessary.

Check camshaft adjuster control valve for debris and if necessary clean thoroughly.

Stretched timing chain problems

If timing chain is stretched past 126 mm maximum range, replace timing chain and tensioner. In addition, replace camshaft adjuster bridge, intake camshaft and spool valve adjuster.

Note 1: Be sure to search for a missing oil screen in camshaft adjuster bridge. See section on Check-valve oil screen problems.

Note 2: Be sure the spool valve piston is level with the retaining clip.

Spool Valve

Jumped timing chain problems

If the distance between camshaft timing marks exceeds 126 mm significantly, there is a chance the timing chain actually jumped one or more teeth and has caused valve-to-piston impact. If this is confirmed, replace cylinder head, timing chain, timing chain tensioner, crankshaft spur gear and crankshaft bolt.