Genuine Audi A3 Intake Valve

Audi A3 Intake Valve Parts and Q&A

• Intake Valve
  06D-109-601-M
  Q: Is thorough cleaning and detailed inspection of the cylinder head and intake valve components essential for determining necessary valve service work during engine overhaul on Audi A3?

  A:

  A detailed cleaning and careful inspection of the cylinder head and valve components are indispensable in establishing the required valve service work in performing engine overhaul. Start by applying an appropriate degreasing agent to the cylinder head to loosen oil deposits and then clean the surface of camshaft bearing areas, hydraulic tappet bore, valve guide and oilway and scrape off the old gasket material being careful not to harm the mating surfaces. Roll the head in order to scrape the carbon deposits off the combustion chambers and ports, then wash all of the head casting using a solvent. Clean the valve heads and stems with a fine wire brush, scraping off the heavy carbon deposits first, and cleaning all other parts thoroughly with solvent, and leaving them to dry thoroughly before reassembling with discarding old oil seals and replacing them with new ones. Check the head castings and look at any form of damage or cracks especially in the area of valve seat and also valve plug/fuel injector holes, where slight cracks can be reused in some engines, but severe damage requires replacement. Repair of valve seats can be done by lapping during reassembly, although any reworking must not exceed maximum allowable dimensions that can be determined by the distance between the valve stem and surface of the cylinder head. Check distortion of gasket surface surfaces Test with a straight-edge and feeler blade and check numerous measurements on the surface of the head gasket and compare with values. In 1.6 litre SOHC petrol engines, machining can be done provided distortion limits are not surpassed, but other engines need head renewal in cases when limits are surpassed. Check wear on every valve, stems being ridged and diameters being measured with a micrometer, a head of the valve not being cracked or badly pitted, shallow pitting being remediable by lapping. Check that the valve stem end face is not over-pitted, which may signify faulty hydraulic tappets, and by vernier calliper check the free length of valve springs, against new parts as springs are usually replaced during major overhauls. Visual inspection is also necessary to check the squareness of all springs and renew distorted springs, and to replace valve stem oil seals irrespective of their condition.