5 Main Causes of Car Engine Low Compression

For those not in the know, “Compression” in engine terms refers to the reaction between air and the car’s fuel. The process brings together a mixture of air and fuel in small amounts within your car’s cylinders, and sees their molecules squashed together under intense pressure. When compression is low, therefore, it can create a number of performance issues in your car, and even cause engine misfires.

Top 5 Causes

Here are the 5 main causes of low compression in your car engine. If you’re familiar with your engine, you might be able to spot them yourself:

1) Cylinder Head Bent due to Overheating

You may be aware that overheating is bad for your engine in a variety of ways. One such negative impact is the crucial cylinder head, needed to close the top of the cylinder to form a proper and efficient combustion chamber, actually soften and bend. When this happens, the misshapen head also don’t allow exhaust to escape properly, nor the proper passage of air to fuel in the cylinder. When the chamber becomes anything but properly enclosed, engine compression drops.

2) Valves are Bent

Valves also play a crucial role in ensuring a proper mix of fluid fuel and air to form together in the combustion chamber (intake valves), as well as gases to escape via the exhaust valves. The engine overheating, along with general wear and tear, can also cause these critical components to get bent out of shape. When this happens, gases can leak from them at the wrong times and via the wrong channels. This means less overall gases traveling the proper route via the exhaust valves, causing a drop in compression.

3) Bad Valve Seals

As with any kind of seal, valve seals are not meant to last forever. Wear and tear will eventually chip away at their efficacy, eventually leading them to need repair or replacement. Worn valves can’t do their job of sealing the valve properly, thus allowing gases to prematurely escape and impacting the engine compression. You might have intake and exhaust valves in good order, but they’re useless when not properly sealed.

4) Bad Piston Rings

Piston rings play a vital role in sealing the cylinder so that combustion can happen efficiently and properly. Their job is to maintain gas compression between the piston and cylinder wall. If the piston rings have succumbed to overheating, they can break, which allows gases to leak through the now-broken seal. Once again, the engine begins to lose compression.

5) Timing Belt/Chain in Wrong Position

Finally, another culprit in falling engine compression is the timing belt/chain. Every combustion engine has one of these components performing its essential role of connecting the camshaft and crankshaft. If this component becomes worn or gets damaged in some other way such as being improperly aligned by a mechanic during a replacement or service, then loss of compression becomes inevitable.

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Low Compression = Poor Performance

If you have reason to believe for any of the above reasons that your car might be losing engine compression, then it’s a problem you must quickly deal with. Engines are finely balanced machines, and if one component is not working properly, it inevitably and negatively impacts the other engine parts. It’s essential to get low compression fixed quickly. Stay safe on the roads.

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