A hydraulic lash adjuster (17;61;81) in which the body (19) defines a body bore (39) extending over substantially the entire axial length of the body, thus making it possible to finish the bore (39) by a more accurate process, such as honing. In the FIG. 2 embodiment, there is a cylindrical member (71) disposed in the lower portion of the body bore (39) cooperating to define a leakdown clearance (39,71 S), to isolate side load on the plunger (25) the leakdown. In the FIG. 3 embodiment, there is both the leakdown clearance (23S,39) between the body bore and the plunger (23) and the leakdown clearance (39,71 S) between the body bore and the cylindrical member (71), the leakdown flow rate of FIG. 3 being variable if the body and the cylindrical member (71) comprise dissimilar metals, having different coefficients of thermal expansion.