The oil pressure regulator is located in the oil filter head. On the oil filter head you will see what looks like a 3/4" pipe plug - under that plug is the oil filter regulator - there will be a spring and plunger. The spring is supposed to be 2.6 inches long and 1.62 inches long compressed, the spring should regulate the oil pressure to 28.4 PSI. Under the spring there is a plunger. Remove the plunger, clean it and the bore. The plunger should move freely in the bore. Torque the pipe plug to 60 ft-lbs on reassembly.