hi guy..i'm new to this forum...i have a problem with one of my excavators, which is Halla 220..its similar to Hyundai 220 using a Cummins 6BTA5.9, and kawasaki Hydraulic Pump,the problem is like this the engine has been overhauled by the previous owner, when i bought it only ran for 70hrs..after that there was excessive black smoke, and lack of power when any of the lever is operated even track...then i pull the machine to my workshop and send the fuel pump and injector for service,change new turbocharger and exhaust manifold, change all the filter including hydraulic filters...but the problem is still there,i even called up a hyd pump mechanic and checked the pressure of the pump..it was ok.The engine starts up in one kick..but when it runs i feel that its draging something..i have operated many excavators and repaired them..but i feel that once the engine is start in a normal excavator we won't hear sound of the hyd hoses pump hyd until we engage the safety lever..but in this machine after i start up i could hear sounds of the hyd pump hyd to the control valve.......pls help me solve this problem..cheers