EGR System

With engine stopped, visually inspect entire EGR system and clean as necessary. Replace hoses that are cracked or broken. Inspect EGR valve for signs of binding or sticking by moving valve diaphragm upwards with finger.
With engine running, check operation of EGR valve and thermal vacuum valve by placing finger on diaphragm of EGR valve and checking diaphragm movement.
With engine coolant temperature below "Closed" value shown in following table, increase engine speed to 3000-3500 RPM. EGR valve diaphragm should remain closed.
With engine coolant temperature above "Open" value shown in table, increase engine speed to 3000-3500 RPM. EGR valve diaphragm should open and allow exhaust gas recirculation.
If EGR valve does not operate as indicated, disconnect EGR valve-to-thermal vacuum valve vacuum hose at EGR valve. Increase engine speed to 3000-3500 RPM and check for vacuum at end of disconnected hose.

If vacuum is present, check EGR, VVT, thermal vacuum, and vacuum delay valves on 310 models. If vacuum is present, on all other models, replace EGR valve. If vacuum is weak or not present, replace thermal vacuum valve.

Thermal Vacuum Valve Specifications

Application

Valve Closed °F(°C)

Valve Open °F(°C)

200SX

Below 95 (35)

Above 95 (35)

210 & 310

Above 140 (60)

Below 140 (60)

280ZX & 810

131-203 (55-95)

⁽¹⁾

510 & Pickup

⁽²⁾

59-140 (15-60)

⁽¹⁾	Below 131 (55) & Above 203 (95).

⁽²⁾	Below 59 (15) & Above 140 (60).

Fig 1: Datsun EGR Valve (All Models)

Courtesy of NISSAN NORTH AMERICA, INC.

Fig 2: Datsun VVT Valve (210, 310, 510 & Pickup)

Courtesy of NISSAN NORTH AMERICA, INC.

Fig 3: Thermal Vacuum Valves

Courtesy of NISSAN NORTH AMERICA, INC.