l EXHAUST EMISSION CONTROLE.G.R. System Description (Cont'd) E.G,R. control valve The E,G.Rr control valve controls the quantity of exhaust gas to be led to the intake manifold through vertical movement of the valve connected to the diaphragm, to which vacuum is applied in response to the opening of the carburetor throttle valve. 3 i Diaphragm spring 4 Valve 2 Diaphragm 5 Valvasan 3 Valve shth s Valvechamber Eczal Thermal vacuum valve This thermal vacuum valve is mounted on the right side of the intake manifold. It detects engine coolant temperature by means of a bui|t~in bi- metal, and opens or closes the vacuum passage in the thermal vacuum valved When the vacuum passage is open, the carburetor vacuum signal is applied to the diaphragm of the E.G.R. control valve to actuate the taper valve connected to the diaphragm. To E,G.R. control valve From camumnr Inspection FUNCTION OF ENTIRE SYSTEM 1, 1) 2) Make a thorough visual check of E.G.R. con trol systems If necessary] wipe away oil to facilitate inspection, If any hoses are cracked or broken, replace. Start engine and place a finger on diaphragm of EtG.Fl. control valve to check for valve opera tion. When engine coolant temperature is below 30C (86 F): Make sure that ErG,R. control valve does not operate when engine speed is increased from idling to 3.000 to 3,500 rpm secqu If ErGtR. control valve operates, check thermal vacuum valve. When engine coolant temperature is above 50C (122F): Make sure that E.G.R. control valve operates when engine speed is increased from idling to 3,000 to 3,500 rpm