Although Nimonic exhaust valves are standard today on most modern diesel engines, Stellite ones are still in use too. The service life of the valve seat area is nowadays very long. As long as there are no fuel abnormalities, blow-bys are mostly a thing of the past. Hot corrosion at the valve disc however still occurs on both Nimonic and Stellite valves and puts a limit on their operating life.
If a valve spindle shows signs of blow-by, excessive corrosion on the bottom of the valve disc or excessive wear on the stem, then it should be replaced or reconditioned. Depending on the valve spindle’s condition, either partial reconditioning or full reconditioning is available at any of QuantiServ’s six reconditioning centres.
Partial reconditioning will involve a grinding of the sealing area, and a re-chroming or HVOF coating of the valve stem.
Full reconditioning involves the complete rebuilding of the valve seat area and of the bottom of the disc by welding. Re-chroming or HVOF coating of the valve stem is also included.
In addition to valve stems we also recondition two-stroke valve seats of any type and make.