Master the AG Mechanics CDE 2025 – Rev Up and Rule the Field!

On overhead valve engines, the valve clearance is corrected by adjusting the hydraulic lifters. This is because the hydraulic lifters are responsible for maintaining the proper clearance between the valve train components. By adjusting the hydraulic lifters, the correct amount of clearance is ensured, allowing the valves to open and close effectively for optimal engine performance.

Option B, grinding the camshaft, is incorrect because grinding the camshaft would actually change the shape and size of the cam lobes, affecting the valve timing and potentially causing engine damage.

Option C, replacing the valve springs, is incorrect as valve springs are responsible for ensuring the valves close properly, not for adjusting valve clearance.

Option D, using a wrench and turning the adjusting nut, is incorrect because overhead valve engines typically do not have adjusting nuts for valve clearance adjustments; instead, hydraulic lifters are used for this purpose.