can anyone tell me about the EGR valve system on the manifold which i think reuses the exhaust gas .Tell me what does it do , and if valve so called switched off can i live with it i was told thatif its a old vehicle it does not matter and how does it work (mechanic disconnect because of the around town co2 build up in exhaust -black smoke - MOT- ) vehicle is a townace auto diesel 4wd . - (#521) winston, 12 Jul 01

EGR recirculates a small amount of exhaust gas when the engine is under partial load, to improve the emissions.It does not operate at high load. There will be no visible difference to the smoke level, it affects only the composition of the gasses. Disconnecting the wires to the solenoid valve will disable it, with no ill- effects. If the EGR valve itself is faulty, it would be wise to make a small blanking plate to seal off between it and the inlet manifold.
It's only fitted to autos, BTW
HTH - (#522) David Miller, 12 Jul 01