Genuine Audi 90 Cylinder Head

Audi 90 Cylinder Head Parts and Q&A

• Cylinder Head
  026-103-265-QX
  Q: How can valves be extracted and reassembled after removing the cylinder head on Audi 90?

  A:

  The valves may be removed with a valve spring compressor equipped with long claws, or by imaginative modification of other kinds of compressors. It can use a piece of tubing with the same diameter as the valve spring cover with the opening being cut on each side or a section can be removed to create accessibility. Tape a board with holes or marked containers to store each of the valves and their parts, where inlet valves are 2, 4, 5, 7, and the exhaust valves are 1, 3, 6, and 8. Squeeze each of the valve springs to screw the collets out, followed by removing the collets and the release of the compressor. Take out the valve spring cover, inner and outer springs and the valve with the springs being the same way to install again. Unscrew the seals of valve stems and take out the valve spring seats. Check the head of the valves, especially the exhaust valves and test the valve seats; any tiny pitting can be dealt with by grinding, but more serious damage may need replacement of the valve and the re-cutting of the valve seat. In re-cutting, it is necessary to measure the distance between the end of the valve stem and the cylinder head in order to prevent excessive removal which might influence hydraulic tappets. Valve grinding requires the addition of coarse carborundum paste, a suction grinder tool and a smooth finish achieved by repeatedly using fine paste. Removal of all carbon and grinding paste on the valves and seats, cleaning of the cylinder head should also be done thoroughly, including examination with a straight edge and feeler gauge; any large gaps require professional re-facing. Check the head of the cylinder, and any cracks, minor ones may be re-used, and inspect valve guides, by placing a new stem of a valve, and observing the lateral movement, a large movement necessitates new guides, which should be a work of a specialist. The valve stem should be reassembled by applying oil to the valve stem, fitting it into the guide, valve spring seat, and a new valve stem seal, which should be covered with a plastic sleeve or a piece of tape to protect it when installed. Install inner and outer valve springs and the valve spring cover making sure to replace springs in pairs. Compress the spring using the compressor to an extent that it is accurate enough to accommodate the collets and ensure that the stem of the valve is seated and tapped to tighten it. Do the same with all valves.
• Cylinder Head
  078-103-351-A
  Q: What are the specific procedures and safety precautions for handling the valves on the Cylinder Head on Audi 90?

  A:

  Follow the procedure given in Part A, but note the following: on the 10-valve engine, the inlet valves are 2-4-5-7-9, and the exhaust valves are 1-3-6-8-10, numbered from the Timing Belt end of the engine. For the 10-valve engine, the minimum distance from the end of the valve stems to the upper face of the cylinder head is the same as for the four-cylinder engine, while on the 20-valve engine, the minimum distance is 36.0 mm (1.417 in) for inlet valves and 36.3 mm (1.429 in) for exhaust valves. The exhaust valves on the 20-valve engine are sodium-filled, and if the valves are being scrapped, they should ideally be rendered safe by cutting them in two with a hacksaw, ensuring that no water contacts them. The valves must then be placed into a bucket of water, as a violent chemical reaction will occur, necessitating the use of safety clothing and goggles. Once the reaction is complete, the valves may be scrapped as normal.