When removing the timing belt, timing belt covers, and crankshaft front seal, one has to pull off the oil pan and pick-up tube/screen. Then, you can remove the oil pump assembly from the engine by unbolting the mountings; and if you cannot get it off easily, the prudent way is to give it a couple of taps with a soft-faced hammer or pry on the casting boss. Pull out the crankshaft oil seal from the oil pump with a screwdriver cover with a rag and be sure not to spoil the seal bore on the body of the pump. Then unbolt the cover and take it off and to prevent any damage to the inner and outer rotor, they should be pulled out of the body carefully. Immersion clean all the component with solvent and check for signs of wear or damage. Here, unscrew the relief valve by unbolting the cap bolt and the washer as well as the spring and the valve in order to inspect for signs of having to be replaced. Be very careful when reassembling to see to it that the relief valve is reinstalled properly so as not to damage the engine. Check the oil pumps' clearance, both the housing and rotors, with a micrometer and feeler gauge, after that lubricate them with clean engine oil before placing them. Pour the oil into the rotor cavities of the oil pump so that the oil is pressed through the layer of the material coating the rotor blades; place the cover on the oil pump and screw it in place. Check and, if necessary, replace the O-ring in the oil discharge passage; apply sealant to the oil pump body and place the rotor in coaxial position with respect to the crankshaft before tightening of the bolts. They include crankshaft seal, pick-up tube/strainer assembly, oil pan, crankshaft sprocket, rear timing belt cover and the timing belt. Last but not the least, replace an oil filter, put fresh engine oil, run the engine and examine for oil pressure and drop and examine the quantity of the new engine oil.