2000 s430, 140,000 miles. Air pump makes a groaning noise when raising the car. It groans a LONG time when i first turn the car on after its been sitting a while, and takes a while to raise the car. at least 2 or 3 minutes. Car also takes a while to raise up when i press the "raise" button for the suspension. Car seems to be leveling fine otherwise. Is this a sign that the pump may be going out, and if so, is it a expensive fix??