603 New Vaccum Pump Noise

[luvthe111]

I started noticing a groaning sound which i think is from my vaccum pump on my 87TD. It only happens when cold, around 1000 rpm when accelerating from a stop and a quieter version of the groan when holding the brakes at a stop when cold. When the engine is warm, I don't really hear it when using the brakes, and its quieter sounding when accelerating past 1000rpm from a stop. I also don't hear it when accelerating the motor in Park/Netural without a load.

Is this normal with the replacement pierburg pumps? This groaning noise started after replacing the pump and the belt tensioner. I never noticed any noise from the original factory setup.