A hard-starting Freightliner Bh 164 can be caused by various issues, often related to the fuel system. While glow plugs are not a factor in this engine, an intake heater might be present on the air intake pipe. However, this shouldn’t significantly affect starting in mild weather. Active ABS and engine lights suggest potential diagnostic trouble codes (DTCs) accessible via the dashboard button. Checking these codes is the first step in diagnosis.
If no further codes are present, ensure the fuel filter is a genuine Detroit Diesel/Mercedes part. Aftermarket filters can sometimes cause issues. Additionally, inspect under the cab for an inline fuel filter within the plastic fuel line, a common feature in older Freightliner Business Class trucks. This filter should be changed or removed if found.
On the engine itself, confirm both the fuel strainer and the main fuel filter have been replaced. Next, examine the fuel supply and return lines at the fuel filter housing. These often use check valve/quick release couplings. Carefully unscrew the female elbow fittings just below the bowl to access and inspect the quick release fittings for debris. This procedure applies primarily to pre-2007 engines.
To further diagnose fuel system problems, connect a line from the engine’s return line to a container. Run the engine and observe the returned fuel for air bubbles, which indicate a potential leak in the supply side. While less common, a faulty injector or fuel leak from the high-pressure lines on the driver’s side can also hinder starting.
Finally, though less frequent, poor condition batteries, cables, or wiring connected to the Engine Control Module (ECM) can cause starting problems. Insufficient power to the ECM may only be overcome when the starter disengages or starting fluid is used. Inspecting these components for damage or corrosion is recommended.
