What may be causing a 1989 Oldsmobile Ninety-Eight to melt EGR's on a regular basis?

Answer 1

The 89 Olds 98 uses a series-1 3800 motor and the EGR valve is a 3 piston unit mounted on a flange with direct access to the exhaust manifold. If it literally melts things, this indicates tremendous heat getting up into the EGR assembly on a prolonged and continuous basis. 1 of 2 things seem possible. 1 The timing on the car is off so badly that the exhaust temp is running constantly way above what is should be. This could be a computer control problem, an O2 sensor issue or a partially blocked catalytic converter in the exhaust. 2 The computer (ECM) also controls the opening and closing of the 3 pintle valves in the EGR assembly - it could be malfunctioning in this area. One last thought - I had this happen - If you get water and then rust up into the 3 small pintle valves and they are then locked open and cannot function, this would allow heat to be exorbitant continuously in the unit and might cause failure. Also, the ECM is "blind" to this as it has no feedback mechanism to know if the electrical signals to these magnetic valves has properly caused them to work in the mechanical sense.