Overhaul of L28/32 Diesel Engine Fitting Valve

Main Maintenance Technology of Valves and Seats for Marine Diesel Engine Parts

Before maintenance, measure whether the distance between the bottom surface of the gas valve and the bottom surface of the cylinder head exceeds the regulation. If this value differs too much, it will affect the compression ratio of the diesel engine and cause the valve to collide with the piston, so the valve seat cushion must be replaced. In the maintenance of DK28 diesel engine parts, the following measurements should be made on the valve after long-term work: the roundness error and cylindricity error after the valve stem is worn. This error can be obtained by measuring and checking the outer diameter micrometer. When these two errors exceed 50% of the clearance limit with the guide tube, they should be scrapped and replaced; the radial runout of the enlightened cone surface should not be greater than 0.003mm. Otherwise, it should be scrapped and replaced.

During inspection, place the valve top between the spindle head and the tail pin of the lathe, and the two thimble pins are in the original processed thimble hole of the valve, and the dial indicator is seated on the carriage, and the contact of the meter is aligned with the air Valve cone contact. The maximum value of the reading change of the dial indicator during one rotation of the valve is the radial runout. At this time, the clamping state of the valve is as shown in the figure above, and the valve is inspected for cracks, pits and pits. The outer surface of the valve stem is allowed to have 10 hair lines with a length of not more than 20mm. The tapered surface and the valve stem connection lock clamp should be magnetically inspected and demagnetized. Those with cracks should be scrapped.