5 Reasons Why Your Car Engine Has Low Compression
Proper compression ensures that gas and air mix in your engine cylinders and ensures operation. However, compression issues can cause problems. Learn the most common causes of low engine compression and the steps you need to take to accurately diagnose the problem.
Top 5 Reasons Why Your Car Engine Has Low Compression
There are many reasons why your car engine’s compression can be low. Sometimes low compression occurs in just one cylinder of your engine, and other times low compression occurs in all cylinders. If compression in a cylinder is low, the engine will start but will likely misfire and the vehicle will run rough. If there is no compression in all cylinders, the engine will not start.
Here are the 5 most common causes of low compression in a typical car engine:
1) Piston Holes
You probably know that your engine has pistons in its cylinders. But when the engine overheats, hot spots form on the piston. After some time, these spots burn and create holes in the piston. When this happens, gas escapes through these holes, causing low compression.
2) Leaking Valves
At the top of each cylinder there is an exhaust valve and an intake valve. Air and fuel enter the intake valve for the combustion process. The resulting gases are expelled through the exhaust valves.
If these valves overheat, they can cause gases to leak out prematurely. When this happens, you get low compression. Often, over time the valve seals wear out, allowing gases to escape and lowering cylinder compression.
3) Timing Belt Wear
All engines have a timing belt or chain that connects the camshaft to the crankshaft. If the timing belt breaks or is damaged, it will not be able to rotate the camshaft.
This means that the exhaust or intake valves will not be able to open or close properly. This prevents combustion in the cylinder and prevents the gases from escaping. This results in low compression.
4) Defective cylinder head gasket
There is a gasket between the top of the engine where the cylinder head is connected. If the cylinder head gasket is defective for any reason and starts to break, a small hole will appear between the cylinder and the cylinder head.
This is called a head gasket blowout, and the gas inside the cylinder will leak through the hole in the gasket. When that happens, you will have low compression and poor performance. If the head gasket breaks between two cylinders, you may experience compression leakage in both cylinders.
5) Faulty piston rings
Piston rings may break or break due to overheating. This causes the rings to no longer be able to seal in the cylinder, allowing carbon gases to leak through the rings. As you probably already know, this type of leak results in low compression.
How to Fix Low Compression
The first thing you need to do is use a compression gauge to see if your engine is actually low compression. This process usually takes 45 minutes, so give yourself plenty of time.
If you don’t have a compression gauge, you can purchase one or take your car to an auto repair shop to have a compression test done. If you find that the compression is low, the next step is to check the cylinders, pistons, valves and seals for damage or defects. You can then replace any damaged ones; however, this will require removing the engine, which is a lengthy and expensive job.