What are the dangers of improper adjustment of automobile valve clearance

Improper adjustment of valve clearance not only affects engine power, fuel consumption, wear, but also noise.

1. The hazard of excessive valve clearance.

The valve opening is reduced, the intake and exhaust resistance increases, the air intake is insufficient, the dynamics are reduced, and the exhaust is not smooth.

Increase the impact force of the valve transmission group on the valve group, and there will be a large abnormal sound.

This creates a phenomenon of "rebound", in which the valve jumps again after it is seated.

It will produce "flying jump", that is, the rising and falling rules of the valve and the opening and closing of the valve do not meet the original design requirements, which will change the phase of the gas distribution and affect the power and economy.

2. The hazard of too small valve clearance will make the valve work not closed strictly, resulting in air leakage, which is easy to ablate the working surface of the valve and the valve seat, and also affects the power and economy of the engine.

The main function of setting the valve clearance:

Because of the high working temperature of the engine, due to the thermal expansion and contraction, it is necessary to leave space for the hot account.

Excessive clearance will lead to untight valve closing, affecting engine work, resulting in insufficient air intake and incomplete exhaust, and collision between the valve and valve seat, valve ringing and other phenomena;

Too little clearance can lead to poor valve closure (no space), noise, increased wear, engine weakness, etc.

Adjusting the valve clearance is considered to be in the most normal working state after the car is in a hot state.

The valve clearance of the intake and exhaust valves is different, and the clearance of the intake valve is definitely smaller than that of the exhaust valve. Due to different models, the requirements for valve clearance are also different, the intake valve is generally between 15-20 wires, and the exhaust valve is between 25-30 wires.

At present, most cars on the market use hydraulic valve lifters, which automatically adjust the valve clearance, which can basically eliminate this phenomenon. Of course, once damaged, it can only be replaced, and cannot be adjusted.

I hope the above can be helpful to you.

Improper adjustment of valve clearance, making the valve clearance too large or too small, will affect the operation of the engine. The gap is too large. After the intake and exhaust valves are opened late, the intake and exhaust time has been shortened, the opening height of the valve has been reduced, the normal valve phase has been changed, the engine has been reduced because of insufficient air intake, the exhaust is not clean, in addition, the impact of the valve mechanism parts has increased, and the wear has been accelerated.

The gap is too small. After the engine works, the parts are heated and expanded, and the valve is pushed open, so that the valve is not closed tightly, resulting in air leakage, power decline, and the sealing surface of the valve is seriously deposed or burned, and even the valve hits the piston.

1. The function of the valve seat is to seal the cylinder by the close fit between its inner cone and the cone of the valve head, and accept the heat from the valve;

2. The valve seat can be directly bored on the cylinder head, the temperature of the valve seat is very high, and it bears the impact load with extremely high frequency, and the wear is serious;

3. The valve seat of many engines is made of better materials (alloy cast iron, austenitic steel, etc.) and then inlaid into the cylinder head.

4. The engine valve is a high-speed moving part, and the quality of the valve maintenance method will affect the quality of the valve and the safety of the occupants.

5. Valves and valve seats are one of the key components that affect the reliability and safety of the engine, which are mainly used to start and close the intake and exhaust channels in the engine working process, control the entry of fuel mixture or air and the discharge of exhaust gas. The working environment of the valve and valve seat is very harsh, in addition to the corrosion of high-temperature gas, but also to withstand the impact of the burst pressure in the cylinder, and the main failure mode is wear.

6. There are usually four types of wear and failure of valves and valve seats, namely contact fatigue wear, high-temperature corrosion wear, abrasive wear and high-temperature creep, and the wear failure process follows the law of general mechanical parts wear, and the creep and corrosive medium at high temperature play an accelerating role in this process.

The valve tightness is determined according to the vehicle condition, not too tight or too loose, improper adjustment of the valve clearance, not only affects the engine power, fuel consumption, wear, and noise.

If the valve clearance is too large, the valve will open and close late and early, resulting in insufficient air intake and poor exhaust, which will reduce the engine power and cause the engine to be noisy. Valve lash adjustment should be done when the engine is cold.

If the valve clearance is too small, the valve will not close tightly, resulting in air leakage, resulting in poor engine idling, easy stalling, carburetor tempering and muffler discharge, and even the working surface of the valve and valve seat will be burned out.

This is because when the engine is working, the parts are elongated due to thermal expansion. If there is no gap between the valve and its transmission parts in the cold state, the valve will be opened due to the expansion and elongation of the valve and its transmission parts in the hot state, which will destroy the seal between the valve and the valve seat, resulting in cylinder leakage, so that the engine power will decrease, it will be difficult to start, and even it will not work normally.

If the valve clearance of the car is large, it will cause the valve to open and close late, causing insufficient air intake and poor exhaust, which will reduce the engine power, and at the same time will cause the engine to appear noisy.

The valve is an important part of the engine, which is responsible for inputting air into the engine and expelling the exhaust gas after combustion. In terms of engine structure, it is divided into intake valves and exhaust valves. The function of the intake valve is to draw air into the engine and mix it with fuel for combustion; The function of the exhaust valve is to exhaust the exhaust gases after combustion and dissipate heat.

Excessive valve clearance will produce running knocking sound, loud noise, accelerate the wear of parts, affect the timing of the valve distribution, so that the valve can be opened or closed at the correct time of Yuyousen, resulting in insufficient air intake, incomplete exhaust, incomplete combustion, black smoke, engine shaking, reducing power, increasing fuel consumption, resulting in weak car operation.

Valve clearance is a necessary inspection item for routine maintenance, and it must not be overlooked.

The 4S shop recommends maintenance every 5,000 kilometers, but if you don't run much, it's okay to maintain it every 8,000 to 9,000 kilometers. After each finch is maintained, you can write down the number of kilometers on your mobile phone during the maintenance, so as not to remember the time for maintenance next time.

The usual maintenance items are mainly to change the oil, oil filter, air filter, air conditioning filter and some routine inspections, such as tires, brakes, etc. If the air filter and air conditioner filter are not dirty, they can be maintained and replaced every two times.

Tires: generally 50,000 kilometers of tire transposition, remember to check the tires for every maintenance, if you find that the tire texture is worn more or even can not see the lines clearly, then you need to replace the tire immediately.

Brake pads: about 50,000 kilometers to replace once, every time you go to maintenance, you also need to check, wear and tear must be replaced, brake problems can not be too inappropriate.

Brake fluid: generally 60,000 kilometers to check whether to replace.

Spark plugs: According to different spark plugs, it is generally 3-60,000 kilometers to check and replace.

Battery: The battery is generally replaced in four or five years, in fact, it mainly depends on your usual use and maintenance, and some car owners can use it for 10 years.

These are just some of the fragile parts, and there are some parts that are not easy to go wrong, as long as they feel smooth while driving, they can be inspected for five or six years.

If the valve clearance is too small, the intake valve will not close tightly, and the engine may leak in the hot state, resulting in a decrease in engine power, increased fuel consumption, and sometimes a carburetor.

tempering phenomenon; At the same time, it will also make the exhaust valve not close tightly, resulting in a decrease in engine compression pressure, a decrease in power, an increase in fuel consumption, and sometimes a phenomenon such as exhaust pipe muffler discharge.

The size of the engine valve clearance varies depending on the vehicle type, but generally speaking, the intake valve clearance is about , and the exhaust valve clearance is . Because the exhaust valve receives more heat during operation and it is also deformed, the clearance of the exhaust valve is usually greater than that of the intake valve.

Valve clearance is an important parameter in the design and manufacturing process of a car, which is set at the factory and can neither be too large nor too small.

The impact of the engine valve clearance on the car clearance valve mechanism parts increases, the wear is accelerated, the clearance is too small, after the engine works, the parts are heated and expanded, and the valve is pushed open, so that the valve is not closed tightly, resulting in air leakage, power decline, and the specific impact of the engine valve clearance on the car:

1. If the valve clearance of the engine is too large, it will cause abnormal metal knocking noise, and may leave traces on the rocker arm, valve stem, etc.;

2. Cause abnormal noise that cannot be eliminated, and large valve clearance will also cause the reduction of intake and exhaust volume, affecting the power and other performance of the engine;

3. The valve clearance of the engine is too small, which will cause the valve to be closed loosely, resulting in cylinder leakage, insufficient compression, large instability of idle limbs, power decline, weak acceleration, tempering or exhaust pipe discharge, easy to stall, increased fuel consumption and other faults, and may also wear out the valve rocker arm and camshaft.

and other components.

Excessive valve clearance:

Affect the timing of the valve valve, the air intake is not sufficient, the exhaust is not thorough, and the engine power is affected;

Knocks will occur during operation, increasing wear.

If the valve clearance is too small, it may cause the valve to be closed poorly, leak air, affect the cylinder pressure, and affect the engine power. A: It can also cause valve ablation.

Adjusting the valve clearance is an important part of the maintenance and must be adjusted as required. The valve clearance is the space left for the valve stem to expand and elongate due to heat and the valve head to move upwards when the valve head is worn.

When a car engine is working, the valves will expand due to the increase in temperature. If there is no gap between the valve and its transmission parts in the cold state or the gap is too small, then in the hot state, the thermal expansion of the valve and its transmission parts will inevitably cause the valve to close loosely.

Reason: The valve clearance is set to ensure the normal operation of the valve train of the internal combustion engine, because the valve train version is in a high-speed state when working, the temperature is high, and the valve will expand due to the increase in temperature.

If there is no gap between the valve and its transmission parts in the cold state or the gap is too small, then in the hot state, the thermal expansion of the valve and its transmission parts will inevitably cause the valve to close loosely, resulting in the engine leakage in the compression stroke and power stroke, so that the power decreases, and it is even difficult to start in serious cases.

In order to avoid this phenomenon, when designing the valve mechanism, a certain gap is left between the tail end of the intake and exhaust valve stem and the adjustment screw on the tappet (or rocker arm) to compensate for the expansion of the valve after heating.

Because of thermal expansion and cold contraction, there should be valve clearance. If the valve clearance is too small, there is a risk that the valve will not be closed properly, causing the engine to shake. If the gap is too large, it will cause abnormal noise.

The valve clearance can be adjusted in some cars, and some cars do not need to be adjusted, and it is a hydraulic tappet. When adjusting the adjustable valve, to open the valve chamber cover, you will see the adjustment screws, measure the gap with a feeler gauge, and adjust the screws at the top. (Now it's generally auto-adjusting).

The larger the valve clearance, the lower the combustion chamber pressure, that is, the worse the power, the greater the engine noise, just bought a new car, the valve clearance is not completely consistent, the best way is to start the car in situ, open the head cover, let the idle run for five or six hours, so that there is no load in the case of a good run-in valve clearance, if you are sensitive to the engine sound, you will find that the engine sound after five or six hours of idle will be much quieter, and the sound of refueling will be much cooler.

The design of the valve clearance is used to improve the combustion efficiency, the valve is too large to enter the combustion chamber too much fuel, so that the combustion is not sufficient, the fuel consumption is increased but does not increase the output, too small is the fuel into too little, although the combustion is sufficient but can not provide a large output, so too large or too small can not work.

The main thing is lubrication, if it is large, the noise will be loud and the power will decrease, and if the oil is not well lubricated if it is small, the power will also decrease.

The valves of the boiler are so large that they emit black smoke. The valve is small and the combustion is incomplete.

1. If the air gap is too large, the opening time of the intake valve will be reduced, and the opening time will be shortened, resulting in insufficient inflation and a decrease in engine power; At the same time, it will also reduce the opening of the exhaust valve, shorten the opening time, and the exhaust is not smooth, resulting in an increase in exhaust gas in the combustion chamber and the deterioration of the engine economy. In addition, it can cause abnormal impact sounds between the transmission parts and between the valves and valve seats.

2. If the valve clearance is too small, the intake valve will not be closed tightly, and the engine may leak in the hot state, resulting in a decrease in engine power, an increase in fuel consumption, and sometimes a carburetor tempering phenomenon; At the same time, it will also make the exhaust valve not close tightly, resulting in a decrease in engine compression pressure, a decrease in power, an increase in fuel consumption, and sometimes a phenomenon such as exhaust pipe muffler discharge.

Hello, I am helping you with relevant information, and I will reply to you immediately. Question: If the valve clearance is too large or too small, will it cause the mixture to be too thick or knock on the cylinder? Turbo Answer Hello Dear!

Here for you to find out that the size of the engine valve clearance varies according to the different models, generally speaking, the clearance of the intake valve is about , and the clearance of the exhaust valve is about . Because the exhaust valve receives more heat during operation, and its deformation is also large, the clearance of the exhaust valve is generally greater than that of the intake valve. Valve clearance is an important parameter in the design and manufacturing process of a car, and it is set at the factory, neither too large nor too small.

If the valve clearance is too large, it will cause the impact sound between the valve transmission parts and between the valve and the valve seat, and accelerate the wear, and reduce the duration of valve opening, resulting in insufficient engine air intake and incomplete exhaust, affecting the engine dynamics; If the valve clearance is too small, it will cause the engine to leak due to poor valve closure in the hot state, resulting in a decrease in engine power and even a burnout of the valve.

Since the valve and its transmission mechanism will wear out during long-term operation, the valve clearance will also change, which requires us to adjust the valve clearance regularly. The vast majority of models are adjusted with adjustment screws, and a small number of models use adjustment gaskets to adjust. Comparatively speaking, it is more cumbersome to adjust the gasket.

2) If the valve clearance is too small, the valve can not be tightly occluded, resulting in the leakage of the mixture, the reduction of power, the waste of fuel, and the uneven rotation of the backfire.