The oil pump is highly sensitive and thus calling for its replacement every time the oil pan is removed is highly recommendable. If there is an idea that the oil pressure is low, then it is mandatory to inspect the oil pressure before following the removal of the oil pan. The initial steps involve the prior elimination of the oil pan; next, two attaching bolts of the oil pump from the block should be removed; finally, it is possible to separate the oil pump and strainer assembly from the block. If the pump is bad, remove it out of the engine and get a new one, in the course of doing an overhaul on the engine, do not scrap the original and try to rebuild the oil pump . To install, rotate the shaft in a manner that has tang of the gear fits into the slot at the lower end of distributor drive and that has the oil pump drive fits into the protruding part of the distributor drive gear. The oil pump should go into that slot rather smoothly; if it does not, the tang needs to be adjusted to create a better fit. Subsequently, fit the pump attaching bolts, and thereafter, tighten them to the torque value suggested. Last but not the least, re-attach the oil pan and pour some oil and on starting the engine ensure that there is no leakage of oil.