Hi guys, I'm having a weird problem with my water temp gauge. When driving, it does not move, stays at the very bottom of the gauge, no matter how far I drive. When I turn the car off and take the keys out, the temp slowly goes up to around what it should be, halfway up the gauge, if I drive a short distance, it's a bit lower. My question is, why does the gauge not work when it should and does work when it shouldn't?