The EGR valve on my 1990 300SE is non-functional due to a leaking (ruptured?) vacuum diaphram. Mercedes wants $400 for this baby, but it is available from Fastlane for less than half ($170). My question is why bother?

Will this affect performance or mileage of my vehicle? It doesn't seem to. However, I would think that the fuel injection system is expecting to see a certain amount of exhaust gas recirculated to the intake mainfold. I can believe that the vacuum leak could have an affect on other functions, but I have not noticed this either, and the line could be plugged easily. Is the intent that this function operates only when the engine is in a warm-up mode?

I would prefer to spend my money on other age-related and needed upgrades to this wonderful vehicle, but I feel the need to understand the function and effect before I decide to ignore it. Any help or advice you can give would be appreciated.

Thanks, Jon