Description
1. Basic functions
Like all tappets, its core function is to be located between the camshaft and the valve stem, precisely converting the rotational motion of the camshaft into the linear motion of the valves to control the intake and exhaust of the engine.
2. Core features of mechanical design:
The mechanical tappet itself is a solid or simple hollow structure and does not have the function of hydraulic automatic compensation. Therefore, a specific and tiny space must be reserved between the top of the valve stem and the tappet - that is, the valve clearance.
3. Gap adjustment mechanism (gasket type) :
Gasket: In this design, there is a "bowl-shaped" recess at the top of the tappet, and a replaceable adjustable gasket is placed inside. This gasket is in direct contact with the valve stem.
Working principle: When the base circle part of the CAM comes into contact with the tantler, the valve is in a closed state. At this point, the gap existing between the gasket and the valve stem is the valve clearance.
Why clearance is needed: When the engine is running, components such as valves will expand due to heat. If there is no cold-state reserved clearance, the valves may not be able to close completely when the machine is hot, resulting in valve burnout, a significant drop in power and other faults.
Iii. Comparison with Hydraulic Tappets
Characteristics: Mechanical tappets, hydraulic tappets
The working principle is rigid transmission. The clearance needs to be manually preset and automatically compensated through oil pressure to achieve zero clearance
A uniform and slight "tap-tap" sound is normal. Theoretically, it should be very quiet. Abnormal sounds indicate a fault
Maintenance requires regular inspection and manual adjustment of the clearance. There is no need for regular adjustment. It relies on the oil system and its own sealing performance
Advantages: Simple structure, reliability, high-temperature resistance, stable performance, maintenance-free, low noise, and automatic wear compensation
The disadvantages include the need for professional maintenance, inherent working noise, complex structure, and high requirements for the quality and cleanliness of the engine oil
Iv. Common Faults and Symptoms
1. Excessive valve clearance (most common)
Symptoms: The engine emits a loud, clear and continuous "tap-tap" sound, and the higher the engine speed, the more urgent the sound becomes. Power may decline and fuel consumption may increase.
The reason is that the top of the valve stem and the gasket are normally worn, resulting in an increase in the clearance.
2. Too small or no valve clearance:
Symptoms: It may lead to poor valve closure, unstable engine idle speed, severe power deficiency, and even backfire and explosion. In severe cases, it can erode the valves.
Cause: Incorrect adjustment during maintenance, or wear and sinking of the valves and valve seat rings.
3. Abnormal wear of tachyres or gaskets:
Symptoms: Abnormal noise, which may be accompanied by wear of the camshaft Angle.
Reasons: Poor lubrication by engine oil, poor quality of engine oil, and quality issues of parts.
V. Examples of Applicable Vehicle Models (Final confirmation by VIN Code)
This part is commonly found in the engines of the following vehicle models:
Hyundai Elantra
Hyundai Tucson
Kia Cerato
Kia Sportage
Specific engine models may include: G4ED, G4GC, G4KD, etc.
