I have a 1986 SDL with 171k miles, but I purchased car with 159k about one year ago. My concern is potential engine damage if EGR blows large amount of carbon into motor.I have no idea if EGR valve has ever been replaced. My dilema is should I try to clean the valve or replace it since I have no history on part. I am also contemplating the BB fix, but I am not sure if there is a downside to this approach. Viewer comments definitely appreciated. P.S. I have noticed some carbon formation around vent hole on EGR valve.