Abstract: A sealed hydraulic tensioner includes a cylinder having a cylinder surface formed in a housing; a piston, received by the cylinder, having an inner surface forming a piston cavity and an outer surface that closely conforms in shape to the cylinder inhibiting the flow of fluid between the outer surface of the piston and the cylinder surface; a tensioner biasing member engaging the piston and the cylinder forcing the piston in an axial direction; a check valve regulating fluid flow between a high-pressure chamber and a low-pressure chamber; one or more apertures formed in the piston extending between the inner surface and the outer surface of the piston that communicate fluid between the piston cavity and the cylinder, wherein a substantially fixed quantity of fluid is encapsulated within the piston cavity and the cylinder.