The trusty 3TN66UJ engine in my restored JD330 started knocking loudly and spewing black smoke then white smoke within 5 seconds of starting to go DOWNHILL on inclines that are 10 degrees or more. This started after running out of diesel and having to bleed the fuel lines. I have re-bled the fuel system to no avail. Runs perfectly normally on level ground or going uphill. Any ideas are welcome!