问：2006 Xterra 4x4，4.0L V6。发动机过热。没有冷却液泄漏。替换恒温器。冲洗散热器。粉丝工作。该怎么办？

06 Xterra，带97K英里。刚刚重建了变速器。在变速器商店的10英里内，它过热。以前从未遇到过热问题。我更换了恒温器并冲洗了散热器。充满新鲜冷却液。第二天发动机以正常温度运行40分钟的开车往返。当我回家时，在车道上过热。没有任何泄漏。变速器商店说，他们在变速器中没有发现水或冷却液的迹象。 The serp belt has proper tension. Water pump shows no signs of failure. Pump/fan shaft is tight and spins freely with little pressure. When it gets hot the coolant in the reservoir looks/sounds like it's boiling. Rad and reservoir cap fit tight. The main fan appears to be working but at what % i dont know. Elec fan comes on when heat rises. So frustrated! I'm not sure what to do next. I am considering the fan clutch but not sure how to troubleshoot that. What could be causing the overheating? I'm mechanically savvy but never messed with the coolant system.

我的车有97000英里。
我的汽车有自动变速箱。