Though the vac system in my '84 300D is not 100% sealed, I do seem to have adequate suction for many of the related components. However, compared to the '84 Euro 300D I just traded this car for, I have to mash the brake pedal an appreciable distance, and with considerable pressure, in order to stop or slow down. The large vacuum lines going to the booster appear new, but I still suspect that my vac pump may be ailing. I have a vacuum tester, but I was under the impression I could only use it to test the vacuum system, and not the pump itself. Is this true? Is there an easy test for the vacuum pump?
Grey/black '84 300D, 194K