Bent Engine Valve Symptoms (and How to Test for It)

Bent Engine Valve Symptoms

One of the many issues that can crop up with your car engine is a bent engine valve. In this article, we are going to discuss the function of engine valves, the symptoms of bent engine valve and the effect this can have on the overall performance of your car engine.

We will also take a look at the ways to test for bent engine valves.

Just in case you are not aware, an engine valve is an important part of your car engine and if there is an issue with it, it is highly advised that you see to it immediately.

What are Valves in an Engine?

Engine valves are the parts of the engine that are responsible for regulating air movement through the motor.

When there is an intake stroke, the intake valves will open so that air can get into the combustion chamber and likewise when there is an exhaust stroke, the exhaust valves will open so that the burnt combustion can be expelled from the combustion chamber.

During the compression stroke both the intake and exhaust valves will work together and remain shut so that enough pressure can be built before the air-fuel mixture can be ignited. The exhaust and intake valves are located in the cylinder head.

We should point out at this juncture that most cars come with two of each per cylinder. That means that a four-cylinder motor will have 16 valves.

But some LS V8 engines come with just one exhaust and intake valve per cylinder.

Symptoms of a Bent Engine Valve

Engine Backfires

One way that you can use to tell that you have a bent engine valve is with how fumes are expelled through the cylinder. Exhaust valves are meant to open and close at specific times, they do not just open and close randomly. This is so that there will always be the right amount of pressure.

So when you have a bent exhaust valve, it could result in a disruption with regards to the timing and can cause it to not seal very well when closed. This can result in an exhaust leak and affect fuel usage.

When your ECU picks up this issue, it could try to change the proportion of fuel that goes to the cylinder. Take note that in a case of an overly rich air-fuel mixture, the unburnt fuel will leak into the exhaust and this results in a popping sound or backfire.

Excessive Oil Consumption

Engine valves are supposed to stay well lubricated in order to function well, but the valve seal prevents oil from getting into the cylinder.

So if the seal is damaged due to a bent valve, oil can move into the combustion chamber. Not just is more oil consumed, but the general functionality of the engine can be adversely affected.

If this issue is not handled immediately, the catalytic converter can get damaged and that is much worse.

If your valve seal is leaking as a result of a bent engine valve, one of the ways that you can tell is when your exhaust pipe gives off blue smoke.

Check Engine Light

Modern cars come with different sensors that keep an eye on different parts of your car engine to ensure that everything is operating smoothly as it should.

So in a situation where something is not right or a part is not functioning properly, you will be alerted to this through your check engine light.

It should therefore not come as a surprise to you, that if any of your engine valve is bent, your check engine warning light will come on. When your check engine light comes on, what you have to do is to check the trouble codes using an OBD2 scanner.

Since engine valves are not electronic, the trouble codes will not read engine valves right away. What it will be reading may be about faulty air-fuel mixture or misfires.

Low Compression

Pressure builds up in the cylinder when the engine is running. This pressure is referred to as compression and when that pressure is low your engine is said to have low compression.

When this occurs, the fuel combustion process will be disrupted and bent engine valves can result in this. This is so because the bent engine valve does not close as it is supposed to and this causes an imbalanced compression.

So if you are running a compression test and you observe that it is low, you should take a look at your engine valves to ascertain whether they are still in good condition.

Lack of Power

Another issue that can arise due to a bent engine valve is lack of power. A valve that is not functioning as it should can cause a reduction of pressure in the cylinder resulting in leakage of the combustion mixture.

Even if the engine tries to compensate by distributing rich combustion mixture, that in itself can still constitute a problem.

It just goes to say that the only way out if you notice that you have a bad engine valve, is to handle the situation immediately otherwise more complications could arise.

Shaking Engine

Bent engine valves disrupt the normal way that your car engine operates and this could result in some shakings.

If for instance the valve became faulty due to a broken timing belt, it can cause misfires and lead to vibrations which you can notice while accelerating or when your car is at idle.

If you have a bad valve, you can still be using the car for a short while but you should get it fixed as soon as possible because valves that are too damaged can make your engine to shut down altogether.

How to Test Engine for Bent Valves

If you want to check for a bent engine valve, the best and sure way to go about it will be to remove the cylinder head and conduct a physical inspection. But understandably, not everyone can carry this out effectively.

Not to worry, there are other ways to conduct the test and they include compression tests and leak down tests.

If you are using the compression test, it allows you to easily know how much compression is produced per cylinder.

The leak down test on the other hand allows you to know whether or not air is leaking out of your engine. To do this, connect the leak down test to the spark plug hole.

When this is done, the crankshaft moves till the cylinder gets to the compression stroke and that is when you will hear the air leaving the engine.

If from the test you notice that the air is leaving through the intake, then it is indicative of a bent intake valve. If the air is leaving through the exhaust points then it is indicative of a bent exhaust valve.

You should note however, that even if air leaves through any of these points, it could also mean something else apart from bent valves. Another thing that it could be indicative of is carbon buildup on the valves resulting in a poor seal.

It is recommended that you contact a professional so that you can be sure of what exactly the issue is.


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