What is the method for adjusting valves on a 4-cylinder diesel engine with 8 valves?
2 Answers
The method for adjusting valves on a 4-cylinder diesel engine with 8 valves is: 1. Remove the rubber tube screws on the cylinder head; 2. Remove the cylinder head nuts and take out the spark plugs; 3. Remove the timing inspection hole cover; 4. Loosen both the intake and exhaust valve screws and bolts simultaneously, then proceed with the adjustment. The operating principle of a diesel engine is: to generate high heat by compressing air, atomizing and injecting diesel through the engine injector, creating an explosive expansion effect inside the engine to push the piston and perform work. A diesel engine consists of the engine block, crankshaft linkage mechanism, valve train, fuel supply system, lubrication system, cooling system, and starting system. Diesel engines are categorized into: 1. Spark-ignition engines: Gasoline engines inject gasoline into the intake manifold, mixing it with air to form a combustible mixture that enters the cylinder, where it is ignited by the spark plug to burn and expand, performing work; 2. Compression-ignition engines: Diesel engines use the fuel injection pump and injector to directly inject diesel into the engine cylinder, where it mixes uniformly with the compressed air and spontaneously ignites under high temperature and pressure, pushing the piston to perform work.
Just finished adjusting the valves on this diesel engine myself, sharing the steps. First, let the engine cool completely, at least overnight—don’t rush in to avoid burns. Pop the hood, get a helper to turn the hand crank, and align the compression top dead center (TDC) mark for cylinder #1 to ensure proper crankshaft timing. Use a feeler gauge to measure the intake and exhaust valve clearances, typically around 0.2-0.3mm (check your vehicle’s manual). If too loose or tight, loosen the lock nut with a wrench, slowly turn the adjustment screw until slight resistance is felt, then stop. Tighten the nut and recheck clearance to ensure no play. Adjust the other cylinders in order (1-3-4-2), resetting the position after each. Finally, recheck all gaps, start the engine, and listen for abnormal noises. It’s not hard, but being meticulous prevents burnt valve seats and engine wear. I do this every 20,000 km to keep performance smooth.
