What are the causes of diesel engine idle vibration?
2 Answers
Common causes of diesel engine idle vibration are as follows: 1. A certain cylinder's fuel injector nozzle is stuck or has poor atomization, causing that cylinder to not work or work poorly (blue-white smoke will be emitted from the exhaust). This can be checked using the cylinder cut-off method. 2. Uneven idle fuel supply from the fuel injection pump, causing uneven operation of each cylinder at idle. 3. Improper idle adjustment (speed too low), which can be resolved by adjusting the idle fuel supply screw. 4. Improper valve clearance (loose adjustment screw or abnormal wear, abnormal wear of the valve push rod, etc.), causing that cylinder to not work or work poorly. This can be resolved by adjusting the valve clearance. 5. Poor valve sealing, causing poor operation. 6. Engine overheating or insufficient oil (causing poor lubrication), making it difficult for mechanical parts to operate.
I've been in automotive repair for many years and have seen plenty of diesel engine idle vibration issues. The main causes include injector clogging or uneven fuel injection leading to uncoordinated cylinder operation; aging or damaged engine mounts reducing cushioning; contaminants in the fuel supply system or fuel pump failure causing intermittent fuel delivery; and stuck EGR valves or intake system leaks affecting air-fuel mixture. I've serviced many customer vehicles where carbon buildup or dirty filters triggered these problems. Untreated, this increases fuel consumption and engine wear. I recommend annual fuel system cleaning and suspension component inspections. If vibration worsens while driving, it's best to pull over immediately and call professional service to check, avoiding safety hazards.
