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DIY: How To Fix Low Compression In One Cylinder

How To Fix Low Compression In One Cylinder

You may or you may not be acquainted with problems in the cylinder but it’s worth knowing what to do when you eventually experience problems with low compression in one cylinder of your engine. This article will provide you a break through of all you have to know to be able to fix low compression in the cylinder on your own. Information is key to know what to do after all so let’s get you through the basics.

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A vehicle’s functionality wraps around the concept of movement. Movement happens through the transformation of energy through the systems in the engine. Fuel and air mix and combustion happens. If you could see through the vehicle’s housing and into the engine, you will see that this process of mixing fuel and air has everything to do with the principle of compression. The gasoline is mixed with the air through the use of the fuel injectors and as this mixture or combination is delivered to the combustion chamber, the mixture gets ignited into the cylinders where the compression happens. The compression created in the cylinders provides the power to move the car and help it function.


Low compression in a vehicle could be problematic. If you have not experienced this problem, you will eventually realize how a big of a hassle it is. When low compression happens in the vehicle, it could either misfire. The ignition system is concerned with misfires, and with low compression in the cylinders, misfires could automatically become the norm for your car. This is bad for your engine. Also, a vehicle experiencing low compression performs poorly. Overall trouble with compression would eventually lead your car to stop functioning completely.

What can cause low compression in one cylinder?


Compression happens in the cylinder. So before tackling the low compression issue, you must first know what is happening inside the part that houses the compression process- the cylinder. Basic knowledge on vehicles tells you that movement or its functionality is connected to power. The cylinder is at the focal point of the power system in your engine. Which means that what happens to cause your vehicle to move, the cylinder is responsible for that. The makeup of the cylinder is metal that is compact and sealed tightly shut. Inside the cylinder is found the piston that moves in an up and down motion in order to compress the fuel. The compression then creates the ignition that is needed for combustion. 


Now that you know how the insides of the cylinder works, it is convincing to say that without the compression, your vehicle and your own driving are in trouble. Low compression will mean less ignition which will cause you misfires. The following is a list of what may be causing your engine to lose compression.


  • The Cylinder Wall may be Cracked

Also called the ‘cylinder block’ usually cracks when there is excessive heat. With the cylinder wall cracked, the compression can be affected. There is a way to know if there is a problem with your cylinder wall. In order to detect the problem, work into the engine leaving the radiator cap open and watch for air bubbles. If there are air bubbles coming out, this means that there is a leak in the combustion chamber that is going through the coolant via the cracked cylinder wall.


  • Trouble with the Gasket

The head gasket is located between the cylinder wall and the cylinder head. Simply speaking, the gasket is the one that keeps everything in order in the engine as it prevents the  coolant from mixing with the fuel as they both travel to the cylinder. Similar to the problem of the cylinder block, overheating is also the main culprit when it comes to gasket issues. Once the gasket gets worn out, it could also cause poor compression in the engine. In order to pinpoint the problem with the gasket, you may use a pressure tester which indicates pressure ratios in the cylinder. Other indications that the gasket is failing is that there is white smoke coming out of the exhaust pipe. 


  • Timing Belt Problems

Well what does the timing belt have anything to do with the issue on low compression you may ask? The timing belts have something to do with the pistons which, as we have discussed a while ago, is the one that creates compression by moving up and down. The timing belts are made up of rubber that latch the crankshaft into the camshaft and control the piston. Problem with the piston is equal to problem with compression. In the case that the timing belt breaks or fails, the camshaft will be unable to function. This in turn will result in the intake valve opening and unable to close while the exhaust valve closes. The gases will get trapped in the combustion chamber. This will cause the problem in compression. As for the piston problem caused by the timing belts, you can detect the problem by pouring thick oil into the combustion cylinder via the spark plug hole. This may lift the issue on low compression a bit so if the compression increases, you have already pinpointed that the problem is coming from the piston.


  • Valve Issues

Valves in the car have different functions in a car. The valves of the vehicle are located in the head. They are in charge of letting in air into the cylinder to undergo the combustion process. The valve letting in the air is called the air intake valve and the other is the exhaust valve where the outgoing air comes out. Usually, the valves break because of interaction with the pistons as it bends. The breakage caused by contact with the piston is commonly resulting from a defective timing belt. Once the synchronization or timing of the motion in the engine is faulty, it would be hard for the valves to avoid friction with the piston. Gases escaping the valves could also cause a lot of damage since it automatically results in valve burns. 


There are also several issues in the valve that could connect to problems with low compression. A dropped valve seat may be a problem in some cases. This happens when a metal ring drops loose from the cylinder due to excessive heat which will then allow air to find its way into the valve port. Another thing that can cause problems with compression is the valve spring getting broken. With the valve spring broken, it cannot fully close which means that it cannot keep in air needed for compression.  


How much does it cost to fix low compression in one cylinder?


When it comes to repair, always keep in mind that if you are taking your car to the mechanic, prices vary depending on your car, the mechanic you ask, the damage of your car. In car repairs, damaged parts should also be replaced and the cost of the replacement is added to the overall repair fee. Repair done by a professional mechanic to fix the low compression in one cylinder, will normally cost you $100 to $200. This is with the repair alone but if you consider the replacement of other damaged parts, the cost will surely vary. Repair of head gasket costs between $1000-$2000. Replacement of piston rings will demand $2000-$4000. But the most problematic would be replacement of the cylinder which would cost you up to $8000. 


But surely there is a way to not incur such huge costs in fixing low compression in the cylinder. So hang in there a moment before we tackle how you can fix low compression in your vehicle’s cylinder by yourself. 

Can you drive with no compression in one cylinder?


As have been discussed in this article, the cylinder is fundamental to your car functioning well. Power operating in the engine is produced in the cylinder; it is where fuel is burned and turned into mechanical energy. Mechanical energy to a vehicle is like food to the human body. But the process of creating mechanical energy from fuel needs to follow a process such as compression. Compression is the beginning of the ignition process.


Inside the cylinder is the piston that moves up and down. The piston is engineered this way to compress the air and fuel mixture together and get to the right amount in order to be converted to mechanical energy needed for the car to move. With low compression, the car would be difficult to start, you will experience misfires. And when worse comes to worst, since it is inevitable if you keep driving a car with low compression in its cylinder, your vehicle will not be able to move at all. 


How do you restore engine compression?


In the above section on the causes of low compression in the cylinder, there are several parts that could be the reason for the issue. So in fixing the problem, you must first know what is causing the problem in order to diagnose the right steps to take. Your vehicle may have a gauge that features or displays information about your car. This data is very helpful since the gauge could tell you a lot about what is happening in the engine, or if there are any complications before they get worse. Doing the repair on your own is quite time-consuming but it could also be worth it if you are determined to save yourself from spending a ton of money for the repairs. Here are steps you could take to fix your low compression problem. Note: if the car has multiple cylinders that are faulty, you might want to consider asking a professional mechanic for help, but if it is only one cylinder that is giving you problems, then you can go ahead and fix the problem yourself.


  1. Make sure that the problem is low compression. Troubleshooting goes a long way. It is very important and if you get it wrong, you might end up damaging your vehicle instead of saving it so give time to inspect well.
  2. Find the prime suspect for low compression. See the causes above (What can cause low compression in one cylinder?)
  3. Make sure to repair or replace the damaged part. In most cases, the timing belt might be the problem. You can fix this by pouring some oil into the cylinder. If this works, you may have also fixed the problem in the piston rings.
  4. Test drive is the best way to know if your repair efforts have been fruitful. Be observant of your car’s performance. You will know if you are doing okay if the misfires do not occur anymore or if the past concerns have now been resolved.


Getting the low compression in the cylinder fixed all by yourself is a challenging task to undertake. It takes a lot of time and effort as well. In order to get better results in fixing it, you must pay attention to troubleshooting as well. There are various reasons why low compression occurs but the main points or parts you could refer to are the piston/piston rings, timing belt, valves. These elements in the engine will help you in your search for the root cause of the problem. Getting the job done on your own may be quite tedious. On the other hand, if the issue is not entirely fixed and is beyond your own capability to fix, calling a professional to resolve the problem may also be a good option. But also to an extent, you have to be willing to spend bucks since repair and replacement of parts are costly as well. 




In summation, problems with low compression in the cylinder could affect the performance of your vehicle greatly. Regular check up of your engine will be very helpful in order to keep even the tiniest piece in good shape and working as it should. Low compression issue manifests itself through misfires. If you ever experience these with your vehicle, then you most probably need to check the cylinders and get it fixed. Whether you fix it on your own or you get it into the garage of professional mechanics, the important thing to do is to be prompt in resolving the issue before things escalate and your vehicle is doomed unrepairable. 


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