What are the effects of excessive or insufficient valve clearance?
4 Answers
The effects of excessive or insufficient valve clearance are: 1. Causing abnormal metal knocking sounds: Excessive valve clearance in the engine will cause abnormal metal knocking sounds, and may leave marks on components such as rocker arms and valve stems, resulting in persistent abnormal noises. It will also reduce intake and exhaust volume, affecting the engine's power and other performance; 2. Decrease in engine power: Insufficient valve clearance will cause the valves to not close tightly when the engine is hot, leading to air leakage and a decrease in engine power, or even burning out the valves. During cold assembly of the engine, a certain gap is left in the valve and its transmission mechanism to compensate for the thermal expansion of the valve. This gap is called valve clearance.
I often hear car enthusiasts complaining about strange engine noises, mostly related to valve clearance issues. When the clearance is too large, the camshaft knocking against the valve lifters creates a clattering sound, affecting the car's acceleration and increasing fuel consumption, making the drive feel sluggish. If the clearance is too small, the valves won't close properly, causing the engine to overheat, emit black smoke from the exhaust, and suffer from incomplete combustion leading to power loss. It may also burn out the valve seat pads. If not repaired promptly, the engine's lifespan will shorten, and repair costs will be high. It's best to regularly check and maintain, especially for older cars, and not wait until the problem becomes severe. Pay attention to engine sounds and temperature changes in daily use—developing good habits can save a lot of money and trouble.
As someone who has worked on many cars, I've seen valve clearance issues quite frequently. When the clearance is too large, the valve tappets become loose, causing abnormal noises during camshaft rotation, accelerated wear, and affecting cylinder pressure stability. When the clearance is too small, the valves stick and fail to close tightly, leading to fuel mixture leakage, excessively high combustion chamber temperatures, and a tendency for knocking or valve deformation. All these issues can harm the engine's overall performance, and severe cases may require an overhaul. I recommend that car owners adjust the clearance on schedule, measure it with professional tools, and avoid tampering without proper knowledge. Maintaining the correct clearance ensures smooth engine operation, reduced noise, and less time spent on repairs. Pay attention to the vehicle's maintenance cycle—prevention is key to avoiding the risk of breakdowns on the road.
I learned the hard way when I was young - excessive valve clearance made the car roar like a tractor, while too little caused rapid engine overheating, foul exhaust smells, and frequent stalling. These issues stem from improper valve operation due to incorrect clearance: excessive clearance increases mechanical collisions and reduces power, while insufficient clearance prevents proper valve sealing, lowering combustion efficiency. Always check before long trips, or you might break down midway. Now I've wised up - I do simple manual adjustments myself, but leave complex jobs to professionals. Well-maintained cars are both fuel-efficient and safe - never overlook these small details.
