Mack MP7/MP8 - TECHNICAL TIPS

ENGINE INSPECTIONS:

• Engine Oil Level - Look not just for Low Oil Level, but HIGH OIL LEVEL. Fuel Dilution from failing Fuel Injectors, Cylinder Washout, Etc, can cause High Oil Levels.  

• Fuel and Oil Consumption - Check with Operator to determine if there has been recent increases in Fuel or Oil Consumption, or other changes in engine performance. 

• Air Leaks - Several engine and DPF components require compressed air, which is obtained from the brake air system. For example, the DPF Fuel Atomization Module will not operate without compressed air (NO REGEN), therefore, repairing all air leaks is incredibly important. 

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• High Pressure Fuel System - The MP7/MP8 engines use a High Pressure Common Rail fuel system. Using PTT test the High Pressure Fuel System to check for internal or external leaks by raising Fuel Rail Pressure and confirming holds at the high pressure over 20,000PSI (worn internal valves in the Fuel Injectors are most commonly the root cause for loss of fuel pressure - requiring new Fuel Injectors and Fuel Connectors to be installed). 

• Oil Leaks - Look closely for any Oil Leaks bleeding through rubber CAC boots. Oil entry into the CAC and Intake is a very common problem due to a failing Crankcase Filter Assembly. This causes Soot/Oil to mix in the EGR System and cause major engine problems.

• CCV FILTER - SOOT/OIL in Intake - A failed Centrifugical CCV FILTER allow Oil and Soot to enter the Engine Intake and Turbo. Serious engine damage and DPF damage will occur, and engine will run poorly.  If high amount of Oil/Soot found in intake, may need to remove the CCV Filter and ensure it is spinning freely and quietly.  

• TURBOCHARGER Damage - Remove the Air Intake Boot to the Turbocharger and inspect the impeller/propeller blades for visible damage. Spin the Turbocharger shaft and inspect for bearing damage and/or play.

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• EGR COOLER - Inspect for soot blockage in the EGR Cooler, or Coolant Leaks. 

• DPF REGEN Full Test - Running a DPF Parked REGEN can provide significant info on the DPF (and engine) Performance. Monitor the exhaust temperatures over duration of REGEN and compare to proper running REGEN.  Exhaust Temps at DPF Outlet should reach ~1,000F.

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• DPF REGEN Full Test (BURNER Style) - For Burner Style DPF Systems, test all major components if DPF REGEN does not initiate correctly (i.e. Fuel Atomization Module, Master Air Valve, Supplemental Air Valve, Fuel Pump, Fuel & Air Pressure Sensors, Ignition Coil, and all Temperature Sensors. When the REGEN is initiated, once the Coil activates, and the Fuel Nozzle supplies fuel, the Flame Temp should rise rapidly to well over 1,000F.

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• DPF REGEN Full Test (CATALYZED Style) - For non-Burner Style DPF Systems, initially when the REGEN is initiated, the Turbocharger VGT Actuator closes to (85-95%) and exhaust temps rise to over 500F. Next the DPF Fuel Injector turns on, and diesel fuel contacts the catalyst, if the catalyst is working correctly the exhaust temperature downstream of catalyst will exceed 1,000F. Older style Fuel Injectors are located just downstream of the Turbo. Newer style Fuel Injectors have a Dosing Module located on the left side of engine, and a Nozzle located downstream of the Turbo.