Valve adjustment for petrol engines. How to adjust valve clearance? How much does a mechanic cost to adjust valve clearances?

Valves are controlled by a shaft with cams and guides. Correct intake and exhaust valve opening times are critical to proper engine operation. Regulation has a direct impact on their closure. If it is not done regularly, it may affect the operation of the actuator and even cause the valves to seize. As you can see, the consequences of negligence are serious. Why is it still worth doing? Check how the valve clearances are adjusted. Read!

Valve clearances - why check valve clearances?

Designers of 4-stroke internal combustion engines use the appropriate valve clearances for this unit. It provides sufficient cooling of the valves due to contact with the seat. The cooling channels receive heat from the valves through contact. And you need to know that these are elements that are exposed to too much heat, because they have direct contact with a combustible fuel-air mixture. That's why cooling is necessary.

Neglecting valve clearance adjustment - what does it lead to?

The operation of the engine and the distance traveled reduce the valve clearance. As a result, the contact time of the valve seat with the element that closes the combustion chamber is reduced. As a result, the valves do not cool properly and can burn out over time. The adjustment of the valves and the gaps created in them aims (usually) to extend the cooling time of the elements. Of course, the reverse situation may also occur, in which the play is so large that it must be shortened. However, one may wonder - can this process be automated?

Hydraulic valve clearance adjustment in the engine. What are hydraulic pushers?

There are car manufacturers who opt for an automatic valve clearance alignment system. Hydraulic pushers ensure correct positioning. They work under the influence of engine oil and constantly adjust the gap according to needs. Of course, such elements are subject to wear and need to be replaced from time to time so as not to damage the valves during movement. Cars of brands such as Honda or Renault have manual clearance adjustment in their engines.

Engine valve adjustment and its consequences

How to check that the gap is not correct? This can be felt when starting a hot engine or while driving. However, in the early stages of backlash change, it will be difficult for you to notice changes in engine performance unless you are a mechanic. What is engine valve adjustment? The regulation contributes to the cooling of these elements and influences their respective opening times. This is reflected in how the drive works. If the clearance is fully reduced, the valve will stick. Too little clearance can damage the valve and cause other undesirable consequences.

Valve adjustment - signs of incorrect clearance

If the valve clearances are equalized to a critical value, a so-called valve hanger occurs. The fact is that with the correct operation of the aggregate, the element will not close:

• the compression in the cylinder will decrease, and the driver will feel this in the form of a drop in power;
• the engine will also run unevenly and begin to twitch;
• there will usually still be a misfire indicator, but this is not the norm. 

If you underestimate the symptoms of visible play and do not make adjustments, you risk a very expensive head repair. Due to the fact that the valve does not close, it overheats and the seat burns out. It is clear that this does not happen immediately, but as a result of a long drive with unadjusted valves.

Valve adjustment in the engine and its frequency

Typically the vehicle manufacturer will recommend when valve adjustment is necessary. How often should the valves be adjusted? This is not a very small distance, usually it is 50-60 thousand kilometers. Then you should go for a service inspection and adjust the valve clearances. No parts need to be replaced other than the valve cover gasket. Thus, you only pay for the disassembly of the lid itself, reassembly and adjustment. Therefore, the entire operation costs 150-40 euros, sometimes more, depending on the size of the engine and access to components.

Valve adjustment on a car with LPG

Installing a gas system on engine models with manual valve clearance adjustment shortens the adjustment interval. Why? The propane-butane mixture has a slightly higher combustion temperature, so the valves may be more prone to overheating. In such situations, it is recommended to make adjustments no more than every 30-15 kilometers. In some engines, it will even be XNUMX, XNUMX kilometers, which can be a bit agonizing. What's the advice on this?

How not to burn gas taps?

There are 3 ways to care for valve seats and the valves themselves when driving on gas. 

1. The first is to program the injection of gasoline at high speeds. Gasoline significantly reduces the temperature in the combustion chamber, which causes cooling of the valves. This is especially important when driving at high speeds. 
2. To make the adjustment less frequent, additional lubrication of the seats with grease is also carried out. 
3. The latter depends on the driver. Skillful driving without frequent use of high engine speeds will take care of the valves.

Should I adjust the valve clearance myself?

If you have such an idea, then you can perform such a service in your home garage. Depending on the engine, you will need:

• gap sensor;
• spanner key;
• flat screwdriver;
• set of keys to remove the valve cover.

However, remember that when changing settings, you must rotate the crankshaft drive pulley and set each piston to the closed position (TDC). It is also necessary to set the clearances for the intake and exhaust valves. Therefore, if you are not sure how to do all this, it is best to contact a mechanic.

Adjustment is usually necessary every tens of thousands of kilometers, and sometimes even earlier. Remember that engine shaking and power loss are practical consequences of valve clearance problems. You would definitely like to avoid them, so make adjustments according to the manufacturer's recommendations.