1. Check pressure reducing valve. Lubricate the plunger with engine oil and check the smoothness of its movement in the hole. If a defect is found, replace the plunger.
2. Check pressure relief valve spring for damage. Measure the length of the spring in the free state and under load, if the dimensions do not correspond to the specified ones, replace the spring. Length in a free state 43.8 mm, under a load of 4.6 kg - 39.1 mm.
3. Using a ruler and feeler gauge, measure the clearance between the pump rotor and the cover. Permissible clearance is 0.040-0.095 mm. If the clearance exceeds the allowable value, the oil pump rotor must be replaced.
4. Using a feeler gauge, measure the clearance between the rotor and the oil pump housing. Permissible clearance is 0.100-0.181 mm. If the clearance exceeds the allowable value, the oil pump rotor must be replaced.
5. Using a feeler gauge, measure the gap between the inner and outer rotor. Permissible clearance is 0.025 - 0.069 mm.