Causes and Symptoms of Low Engine Compression

The internal combustion engine mixes air and fuel together in the cylinder of an engine where it is ignited. The right ratio of air and fuel is extremely important for the smooth function of the engine. Low engine compression means the cylinders are unable to compress enough air, which in turn hinders the engine’s performance and efficiency. Let’s begin with the most common causes symptoms of low engine compression.

Common Symptoms of Low Engine Compression

A mechanic checking the engine compression pressure — You must keep a check on the signs of low engine compression

There are many issues your car may face due to low engine compression. If the compression is low, it may misfire or malfunction completely. However, if your car has a low engine compression in all the cylinders, it probably won’t even start. This is why it is important to know the early symptoms of low engine compression.

Engine Misfires

It is one of the common signs of low engine compression in one cylinder. The misfire occurs when the engine skips one of the steps of the combustion cycle.

Loss of power

Misfiring in the engine also leads to the loss of power. Besides, it makes a car jerk as it moves. The loss of engine power is directly proportional to the number of affected cylinders.

For example, if 2 cylinders out of 4 are misfiring, that will reduce 50% of the engine power. Hence, you might be able to take short trips but cannot drive on elevated or uneven terrain.

Poor Fuel Economy

A sign show fuel economy — A poor fuel economy can be the sign of low compression engine

Poor engine performance will also lead to poor fuel economy because a higher compression ratio always gives better fuel economy. In case of low compression, your engine burns more fuel than it should. Hence, if you ever notice a low fuel economy, always check for other symptoms of low engine compression.

Failure to Start

Another symptom of low engine compression could be a failure to start a car. If all engine cylinders have low engine compression, then your car will not start no matter how hard you try to make it operational. This happens because your car engine does not have enough pressure to ignite the air-fuel mixture.

What Causes Low Compression Engine

There are several reasons that can lead to low engine compression. Sometimes it happens in one cylinder; while sometimes it may exist in all engine cylinders. Here are some common causes of a low compression engine.

Holes in the Piston

A piston is often made of alloy and can tolerate high engine temperature. However, they become weak over time and may develop hot spots if there is an engine knocking or the engine is running too lean. In any case, these hot spots can turn into burn holes and cause piston gas leakage into the combustion chamber.

Besides, pistons can also get damaged in high mileage engines which ultimately cause lower compression over time.

Worn Timing Belt

A worn out timing belt — A worn-out timing belt can also cause a low compression engine

The timing belt in an engine connects the camshaft and crankshaft. However, if the timing belt is worn out the camshaft won’t turn properly. Meaning, it won’t be able to intake valve properly or open and close the exhaust valve as expected. Hence, the combustion process will stop and no gases can be released.

Head Gasket Failure

The head gasket is located on top of the engine and leaves small holes between the cylinder and its head. This is called a blown-out head gasket where the gases leak out of the gasket holes. When this happens, your car performance goes down and will have a low compression engine. However, if the head gasket fails between those cylinders, then there is a chance that you will have low compression in only two cylinders.

Broken Camshaft

A broken camshaft can fail the crankshaft and make it difficult to push the piston properly. The absence of this pressure can be the reason for low engine pressure. You can take a compression engine test to confirm.

Leaky Valves

Every engine’s cylinder comes with an intake and exhaust valve. The intake valve permits fuel and air in, whereas the exhaust valve lets the gases out from the ignition cycle. At that point, when these valves become exhausted due to an excessive amount of heat, they might begin spilling gases out.

Conclusively, keeping a car maintenance schedule can help you identify the issue before it starts going bad.

With this, we conclude our guide on the low engine compression symptoms and causes. However, if your car engine just broke down and you want to buy a used car for sale in the UAE, then take a look at the following list:

If you find the guide informative, stay tuned to the UAE’s leading auto blog for more.