Checking hydraulic tappets - Audi MB/1B/MC-2 engines

• Checking hydraulic tappets
  • Tappets cannot be adjusted or repaired
  • Irregular valve noises are normal when starting engine
  • Oil filter should have anti-drainback valve (e.g. Mahle OC85)
  • Oil should be correct weight for engine
  • Start and idle engine until radiator fan runs
  • Increase engine speed to 2500 rpm for two minutes
  • Tappets rotate during operation - a tick cycling in loudness (ca 5 seconds) indicates a weak tappet
  • To locate - stop engine and remove cam cover
  • Rotate engine until cam lobe above tappet to be checked points upwards
  • Press down on tappet with a wooden or hard plastic wedge - if there is more than 0.1 mm of travel before the valve opens, renew the tappet

Do not restart the engine for 30 minutes after fitting new tappets.