Valves out of adjustment symptoms

Valves are crucial mechanical components in the car engine that restrict or allow the flow of air in and out of the cylinder. If the valves are not in good shape, it will result in poor engine performance or rough idle because the engine is not operating at its peak efficiency.

What is a valve adjustment?

Engine parts, especially valve mechanisms and valves themselves, operate at a very high temperature, and, as the metal heats up, it expands, resulting in an elongation of the valve. Thermal gaps are necessary to compensate for this expansion, and adjusting these gaps is known as a valve adjustment.

Valves can sometimes get out of adjustment due to the constant stress that is subjected to. Knowing when the engine valves have adjustment issues on time can help you fix the problem on time before it causes more damage to the engine that will cost you a lot of money to repair.

So, how can you know that your engine valves are out of adjustment? In this article, we will tell you signs that could indicate this valve issue.

How do I know if my valves are out of adjustment?

A sure sign that your valves are out of adjustment is if the engine keeps making loud tapping or clicking noises when you start up the engine or when you experience a loss in engine power. Another sign that indicates your valves are out of adjustment is if your car has a rough idling time, especially before it warms up. The rough idling is caused by the valves opening late, thus choking the fuel.

Common symptoms that your valves are out of adjustment

1. Your engine makes loud tapping or clicking noise

One of the common symptoms of valves that are out of adjustment is if your car engine keeps making loud tapping or clicking noise.

The reason why the engine is making this noise is because of friction with the cylinder. If the problem is not fixed quickly, your car will gradually lose power because of decreased engine performance.

2. Overheating

Another sign that your valves are out of adjustment is if the engine keeps overheating. When the valves are not adjusted correctly, they will close slower than they should, making the engine not dissipate heat properly causing it to overheat.

3. Increased fuel consumption

If you notice that your car consumes more fuel than it used to, then your valves could have adjustment issues. The exhaust valve will open while the intake valve is still taking in air and fuel onto the combustion chamber.

This means that fuel could come in and out of the exhaust valve resulting in more fuel consumption.

4. Pre-ignition issues

If your car has pre-ignition issues, then that is a sign that the valves have adjustment problems. Pre-ignition usually occurs when fuel in the combustion chamber is ignited before the spark plug fires.

When the valves are out of adjustment, the valve clearance is reduced causing the engine to heat up quickly. If the heat becomes too much, it will ignite the engine before the spark plug fires up.

What happens when your valves are out of adjustment?

When your valves are not adjusted your engine efficiency will drastically reduce because it is not breathing normally. More so, valves will leak exhaust gas past the valves, leading to a catastrophic failure of the engine.

Your engine will also not operate at full power and is likely to burn fuel quickly. Your engine inefficiency will also result in increased exhaust smoke.

What value should the thermal gap be when the valve is adjusted?

In general, the value of the thermal gap is, very small, about 0.1-0.4 mm. In this case, it is usually determined with a set of feeler gauges in increments of 0.05 mm or less.

The thermal clearance for intake and exhaust valves is different: because the exhaust valves get hotter, therefore increase in size more and require more thermal clearance.

How to know when to adjust the valves?

Depending on your car’s make, model, and engine, you should find this info in your owner’s manual. In general, this procedure is not performed so often, usually every 50000 to 80000 kilometers or 31000 to 50000 miles. 

However, a more frequent check is also a good thing, especially if the car is equipped with LPG installation since LPG fuel increases the thermal load on the engine.

Will valves out of adjustment cause misfire?

YES, valves with adjustment issues can cause a misfire. A misfire is when one or more cylinders are not producing enough power.

If the valves are adjusted too tight, they will cause a misfire. Out of adjustment valves will also affect the air-fuel mixture which will. in turn. affect the ability of the cylinder to produce enough power.

Will a valve adjustment increase compression?

Incomplete valve closure is caused by reduced clearance, which then leads to a number of adverse consequences. If there is a leaky combustion chamber due to a partially open valve, hot gases leak into the intake or exhaust systems and cause a drop in compression. 

Will a valve adjustment increase performance?

YES, valve adjustment will increase your engine performance because the engine will become smoother and more responsive. When valves are well adjusted, the engine will burn fuel at maximum efficiency and that will increase its performance drastically.

Do all engines need valve adjustment?

No, not all engines need this procedure. It depends on whether the motor is equipped with hydraulic compensators – these devices are meant to automatically adjust the thermal gap being helped by the engine oil supplied.

However, these devices are also prone to wear and tear, so the above symptoms might be subjected to these engines as well when the hydraulic compensators are bad.


Valves that are not properly adjusted can affect the performance of your car by reducing engine efficiency. It can also cause massive damage to the engine if the problem is not fixed immediately.

So, if your vehicle is showing signs of out of adjustment valves, take it to a trusted mechanic for a thorough inspection and repair.

Adjusting the valves must be done by qualified personnel because is not an easy operation.

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