Valve clearance adjustment is an essential maintenance task for many internal combustion engines. Proper valve clearance ensures that the engine’s valves open and close correctly, allowing for efficient fuel combustion and optimal engine performance. However, not all engines require regular valve clearance adjustments. In this article, we will explore what valve clearance is, which engines need this adjustment, and the importance of adhering to the manufacturer’s maintenance schedule.
Understanding Valve Clearance:
Valve clearance refers to the small gap between the engine’s valves and the corresponding camshaft or rocker arm. This gap is necessary to accommodate the expansion of engine components as they heat up during operation. If the valve clearance is too tight (valve lash), the valves may not fully close, leading to poor performance and possible damage. On the other hand, excessive clearance can cause noise, reduced power, and accelerated valve wear.
Engines Requiring Valve Clearance Adjustment:
- Overhead Valve (OHV) Engines: Many older vehicles and some modern small engines, such as lawnmowers and motorcycles, use OHV designs. OHV engines typically require periodic valve clearance adjustments due to their mechanical valve train setup.
- Single Overhead Cam (SOHC) Engines: Some SOHC engines have mechanical lifters or adjustment mechanisms that necessitate valve clearance adjustments.
- Diesel Engines: Many diesel engines, especially older ones, have mechanical valve train components that may require periodic valve clearance adjustments.
Engines Not Requiring Valve Clearance Adjustment:
- Double Overhead Cam (DOHC) Engines: Most modern DOHC engines have hydraulic lifters, which automatically adjust the valve clearance as needed. These engines do not require regular valve clearance adjustments.
- Some SOHC and Inline Engines: Some modern SOHC engines and inline engines use hydraulic lifters or self-adjusting mechanisms, eliminating the need for manual valve clearance adjustments.
Importance of Adhering to Manufacturer’s Maintenance Schedule:
Checking and adjusting valve clearance at the recommended intervals is crucial for the engine’s longevity and performance. If your engine requires this maintenance, neglecting it can lead to various issues, including:
- Poor Engine Performance: Incorrect valve clearance can result in poor fuel combustion, reduced power, and decreased fuel efficiency.
- Increased Wear: Inadequate valve clearance can cause excessive valve wear, potentially leading to expensive repairs.
- Noisy Valvetrain: Tight or loose valve clearance can result in a noisy valvetrain, producing loud tapping or clattering sounds.
- Potential Engine Damage: In extreme cases, improper valve clearance can cause valve-to-piston contact, leading to severe engine damage.
Checking and adjusting valve clearance is a critical maintenance task for engines that require it. While many modern engines are equipped with self-adjusting mechanisms or hydraulic lifters, older engines and certain small engines may still need regular valve clearance adjustments. It is essential to refer to your vehicle’s manufacturer maintenance schedule and consult with a qualified mechanic to determine if your engine requires valve clearance adjustment. By adhering to the recommended maintenance intervals, you can ensure your engine operates at its best and prolong its lifespan.
