Genuine Mazda 929 Valve Spring

Mazda 929 Valve Spring Parts and Q&A

• Valve Springs
  JF01-12-115B
  Q: How are valve springs serviced and what precautions should be taken during the process on Mazda 929?

  A:

  Valve springs are not normally removed until the Cylinder Head in the engine is removed, but can be removed in place with the head mounted provided there is an air compressor and an adapter. The spark plug connecting the valves into the cylinder head is connected to provide compressed air to the combustion chamber. A lot of care should be taken in this process since when the valve retainers are removed, the valve may fall in the cylinder bore and hence require the removal of the cylinder head before it can be recovered. The head assembly should be removed in order to pull off the valve springs with the head off. In case the head is still on the engine, the rocker arm cover and the rocker assembly must be removed, with the crankshaft re-arranged in such a way that the cylinder to be worked on is positioned at TDC and the valves closed to ensure that the air pressure is maintained. The fitting is then fitted in as per the instructions of the manufacturer, and pressurized which needs a lot of pressure. The valve spring is then compressed using an appropriate tool until both of the valve keys can be removed out of the groove in the valve head. Once the keepers have been removed, the spring tension is discharged gradually, and the spring retainer and the valve spring are removed. To work on an installed cylinder head, a strip of string could be tied to the top of the valve in case it falls into the combustion chamber in case there is loss of air pressure. To install, the valve spring and spring retainer should be placed over the valve stem and then the spring is compressed until the keeper groove is fully revealed. The keepers are then safely placed into the groove, the spring tension is discharged and the compressor tool is removed and the spring pressure on the retainer is left to fix the keepers in place. The valve springs should be inspected as to whether they are broken or corroded and replaced where necessary. The free length should be checked against specifications, and limits of the free length are different in relation to the type of engines. Also, there are engines where the valve springs need to be checked flat against a straight surface and the maximum distance between the top of the spring and the surface checked with certain limits depending on the engine model.