REMOVAL & INSTALLATION
The oil pressure relief valve acts as a safety valve which opens when the oil pressure becomes too great. When the engine is cold, the oil is thick, which makes it easier for the oil pump to move it. This in turn creates greater oil pressure. On a cold engine, the oil pressure relief valve plunger is in its lowest position and allows only some of the oil to travel to lubrication points: the rest is fed back into the crankcase. This prevents the oil pressure from raising high enough to burst the seals in the oil cooler and elsewhere. As the engine warms, the plunger rises because the thinning oil doesn't have as much pressure as it did when cold, and more oil is directed toward the lubrication points.
The oil pressure relief valve is removed by unscrewing the end-plug and removing the gasket ring, spring, and plunger. If the plunger sticks in its bore, it can be removed by screwing a 10mm tap into it.
On 1600cc engines, the valve is located to the left of the oil pump. On Automatic Stick Shift models, it is located on the oil pump housing. On 1700, 1800 and 2000 engines, the valve is located beside the oil filter.
Before installing the valve, check the plunger for any signs of seizure. If necessary, the plunger should be replaced. If there is any doubt about the condition of the spring, it should also be replaced. When installing the relief valve, be careful that you do not scratch the bore. Reinstall the plug with a new gasket.
Type 4 and Type 2/1700, 2/1800, 2/2000 engines have a second oil pressure relief valve located just to the right of, and below the oil filter.