Genuine 2004 Volvo V70 Cylinder Head

2004 Volvo V70 Cylinder Head Parts and Q&A

• Q: What are the steps involved in dismantling, inspecting, and reconditioning a cylinder head on 2004 Volvo V70?

  A: New and re-conditioned cylinder heads are available from the manufacturer and engine overhaul specialists, and specialist tools are needed for the procedures of dismantling and inspection, with the replacement of new components potentially being difficult to find. For home mechanics, buying a reconditioned head may be more practical and affordable than trying to dismantle, inspect and recondition the original head. To dismantle, the cylinder head must be removed, then if applicable, the camshafts and tappets. Remove the thermostat housing, spark plugs, and any other unions, pipes, sensors, brackets, etc. that may be needed. Tap the valve stem of each to release the spring, then use a deep-reach valve spring compressor to expose the collets, which can be lifted out using a small tool. Remove the valve spring upper seat and spring and pull the valve out of its guide. Use pliers to remove the valve stem oil seal scraping any carbon build-up around the valve guide before recovering the lower seat. Store each valve with collets, spring and seats in labelled bags to ensure their sequence. Clean all gasket material from cylinder head surfaces with a suitable dissolving agent and a soft putty knife taking care not to use metal scrapers. Remove carbon from combustion chambers and ports, remove oil deposits and clean the head thoroughly and dry completely. Inspect the head for cracks and damage to the surface of the gasket for distortion using a straight-edge and feeler blade. Examine valve seats for pitting or cracks, if valve guides are worn they must be replaced. Clean threaded holes in cylinder head so you can read torque accurately during reassembly - use a tap to clean damaged threads. Check each valve for wear and damage (valve stem diameter can be measured by a micrometer). If satisfactory, grind in the seats of the valves using appropriate grinding compounds, making sure the valve provides a smooth gas-tight seal. After grinding, clean off any traces of the compound. Examine valve springs for damage and measure their free length, replacing any that are distorted or have lost tension. Renew valve stem oil seal No matter what condition it is in, it can renew the oil seal. For reassembly, put some oil on the valve stem, insert it into the guide of the valve stem, and install the spring lower seat. Use a fitting sleeve or polythene to protect the new oil seal when fitting the valve and then fit the valve spring and upper seat, compressing the valve spring to fit the collets. Tap the stem of the valve to assure proper seating of the collets, repeating this for all of the valves before refitting all other components and the cylinder head.