This hydraulic pump gasket seals the joint between the pump housing and the mounting face on the host tractor. It prevents external oil leakage and maintains system pressure at the pump outlet. A degraded gasket allows air ingress or fluid weep, which reduces pump volumetric efficiency and can lead to cavitation damage. The gasket is manufactured to the original profile so it matches the seal groove geometry of the pump housing. On reinstallation, clean both mating surfaces and replace the gasket; do not reuse a compressed gasket.