How to Adjust the Valves on a Four-Cylinder Engine?
2 Answers
Four-Cylinder Engine Valve Adjustment Method: Rotate the first cylinder to the compression top dead center (there is a scale on the crankshaft pulley or a mark on the crankshaft flywheel) aligned with the 0 scale line or the pointer in the timing gear chamber. Adjust the intake and exhaust valves of the first cylinder, the intake valve of the second cylinder, and the exhaust valve of the third cylinder. Then rotate 360 degrees to adjust the exhaust valve of the second cylinder, the intake valve of the third cylinder, and the intake and exhaust valves of the fourth cylinder. The function of the valves is to specifically input air into the engine and expel the exhaust gases after combustion. Structurally, the engine is divided into intake valves and exhaust valves. The intake valve's role is to draw air into the engine to mix with fuel for combustion; the exhaust valve's role is to expel the burned exhaust gases and dissipate heat.
I frequently perform car repairs and maintenance, and adjusting the valve clearance on four-cylinder engines is quite common. The first step is always to let the engine cool down—measuring when it's hot is inaccurate and can easily cause burns. Use a feeler gauge to measure the clearance between the valve stem and the rocker arm. For most four-cylinder cars, the standard range is 0.15 to 0.25 millimeters, but always check your car's manual for specifics—don't guess. Rotate the crankshaft to position each cylinder at top dead center (TDC) in the compression stroke, adjusting them one by one. Loosen the lock nut, turn the adjusting screw until the feeler gauge has slight resistance—just enough to slide but not too loose—then tighten the nut to ensure stability. After adjusting all the valves, reinstall the cover and start the engine to test for smooth operation. If the clearance is too small, it can cause valve burning or cam wear; if it's too large, it will create knocking noises and increase fuel consumption. I recommend checking every 30,000 kilometers—it's a simple but crucial maintenance task that can extend engine life and save on repair costs. Beginners will get the hang of it after a few tries, so don’t be afraid of the hassle.
