问:20 - 30分钟后发动机过热。为什么?

过热。我最近有透射重建。在20分钟的驾驶它过热。没有任何形式的泄露。取代了恒温器,清洗散热器,加适当的冷却剂,打嗝系统。第二天,我开车去工作没有问题。大约25分钟车程,主要是高速公路。开车回家和汽车过热对我到车道上。检查了球迷,软管和都很好,球迷按预期工作。取代了散热器盖,顶端冷却剂。 Drove again for roughly 30 minutes around the neighborhood and it overheated again. I am thinking water pump. It doesn't leak and the pully feels secure. What makes me think water pump is because I removed the radiator cap and started the car after letting it warm up. Looking in the cap opening, I saw no movement of fluid with the engine running. Also, the lower hose feels very soft while running. Shouldn't I see some fluid movement? Could it be a water pump? '06 Xterra, 4x4, 4.0L v6, 97K miles

我的车有97000英里。
我的车有一个自动变速器。