The oil level on my K2 tank falls off the dipstick within 2-3 hours of engine shut down. When I installed the oil pump at the last engine re-build I checked that the oil shutoff valve in the oil pump was seating o.k. [I couldn't suck any air past it by mouth]. The oil tank held it's level at first when I started running in, but now it won't. I don't like it because it now takes more than 5 seconds for oil light to go out because the oil pump has to bring oil up to tank before it can build pressure. Can the oil drain through the pump without going through the shutoff valve?