hi captaincrunch:
In nutshell, EGR is a Diesel engine killer. It will not hurt to completely bypass the EGR valve. This can be done by inserting a ball-bearing or a rubber plug into the rubber connector at the EGR valve. This will also improve the performance and mileage on the car.

The other valve is an Air-recitculating valve which sits on turbo unit. That too can be blocked esp for cars that have no cat converter or trap oxidizer. It does not affect the function of turbo but will give you a slightly enhanced performance and also a bit smoother shifts without clunck. This valve can be blocked the same way as EGR. This valve also is the culprit resulting in surges while the car is on cruise control.

A slight whistle is typical of all turbines or turbo. and that noise should not be confused with excessive whistling due to ARV.

Hope this helps.

MVK

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One penny saved is three penny earned.

1985 300D Turbo 179,000miles