A valve system (44) for reducing morning sickness effects in a viscous clutch (20) having a reservoir (38) with a bore (46-1) includes a valve element (44-1), a counterweight portion (44-2), a pivot (44-3), and a biasing member (44-4). The pivot is located in between the valve element and the counterweight portion, and the valve element and the counterweight portion are configured to commonly move about the pivot between open and closed positions. The biasing member is configured to bias the valve element to cover the bore in the closed position by default. The counterweight portion is configured to counteract the biasing member under centrifugal loading such that the valve element at least partially uncovers the bore in the open position.