My 3306 exhaust manifold is overheating when I put a larger load on it. The rest of the engine stays at 180 degrees no matter how big the load is. It never gets hot. We've changed the manifold, the turbo and housing, thermostat, adjusted the timing of engine and injection pump, added a bleeder line to the manifold but it still gets hot. As soon as we put a good size load on it, it instantly starts making air from the turbo and going into the top of the manifold. We can Crack our blended line and watch it instantly happen. The larger the load the more air it creates. As soon as the load comes off, the air will shortly follow and go away. The manifold had always operated at 232 degrees. But it starts climbing right away from steam and air with a load. And I'm not running anything that I haven't run before on it. It used to carry these loads no problem. And once again... the entire engine is cool and 180 degrees. Can anyone help me out with this?