Isuzu - TECH TIPS

The following lists all common Technical Tips for Isuzu Engines and DPF/SCR Systems.

For Pre-2010 engines, discard all maintenance items relating to the SCR System (I.E. SCR and DEF items).

For best diagnostic results use Isuzu IDSS2 software with NEXIQ2 adapter.

TIPS!

Engine Oil Level - Look not just for Low Level, but HIGH LEVEL. Fuel Dillution from failing Fuel Injectors, Cylinder Washout, Etc, can cause High Oil Levels (in addition to Coolant Entry).
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.
Diesel Fuel and DEF Fluid - Smell the Fluids to ensure correct. Contamination in fluids is a major problem in diesel applications.
BOOST LEAKS - On Isuzu 4HK1 engines, either side of the Charger Air Cooler (CAC) utilizes either plastic or rubber boots. There is also a rubber insert that seals the CAC Outlet Tube to the plastic Boost Tubing. The rubber boots and inserts fail often, causing a boost leak, causing the engine to run poorly and clog the DPF frequently. Look for wetness at the CAC Boots, and look closely for damage to the rubber/plastic CAC items.

FUEL INJECTORS - The (4) Engine Fuel Injectors can fail relatively frequently on Isuzu 4HK1 engines, especially when poor fuel quality is evident. Faults relating to "Low Fuel Pressure" or "Large Fuel Leak Detected" may occur when the Fuel Injectors are seriously worn. Running the engine at fast idle, or using the Fuel Rail Pressure Test in IDSS2 may be used, to confirm that the Fuel Rail Pressure can hold at ~20,000PSI for over 1 minute. (Be aware that other High Pressure Fueling Components may also fail, such as the Fuel Press Sensor, Fuel Regulator, HPCR Fuel Pump, etc).

SOOT in Intake - The Isuzu engine utilizes an EGR Valve and small Closed Crankcase Breather. Over time these items wear out and can allow Soot/Oil to enter the engine intake. Replace the EGR Valve and/or CCV Filter as needed.
EXHAUST (BRAKE) VALVE - The Exhaust Valve located just upstream of the DPF System is actuated by Air Pressure / Vacuum from a pump on the opposite side of the engine. Often the rubber hose becomes damaged, or the solenoid valve itself seizes and requires repair. This Valve is crucial for the DPF REGEN to occur. Isuzu IDSS2 can be used to test the Valve, to ensure cycling from 0-100%, you can listen for an engine tone change when cycling the valve.

DPF REGEN Full Test - Running a DPF Parked REGEN can provide significant info on the DPF (and engine) Performance. Look at Exhaust Temps over duration of REGEN and compare to proper running REGEN. Once the REGEN is initiated, the Exhaust Valve closes, and the exhaust temps rise to over 500F. Next diesel fuel is sprayed into the exhaust (either through the engine fuel injectors or a DPF Fuel Injector - depending on the engine year), the exhaust temperatures upstream of the DPF Core should exceed 1,000F.