Engine Compression Test

For the engine to run smoothly, it is necessary that each cylinder sports equal engine compression ratio. Irregularity of engine compression in different cylinders will eventually show in form of adverse effects on the performance of the vehicle. The best way to check whether poor engine compression is the reason for the poor performance of the car, is to carry out an engine compression test on it. This test doesn't just help you detect the compression levels in different cylinders, but also helps in detecting various engine problems, which - in turn - helps you initiate repairs before these problems become irreversible.

Engine Compression Test Methods

Basically, there are two methods:

• Manually Testing With a Compression Gage
• Electronic Testing With an Engine Analyzer

Both of these methods have their own advantages and disadvantages. If you plan to carry out this test on your vehicle on your own, you should ideally choose the manual method, which is relatively easy to execute.

Manually Testing With a Compression Gage
You will require a compression gage to test engine compression. The foremost thing you need to do is to disable the power to the ignition or fuel system. This can be done by removing the ignition coil connector or fuel pump fuse. Ideally, you should check the ignition system to ensure that power is genuinely disabled. Remove the spark plug from the first cylinder, and insert the compression gage into it. Once the gage has been properly inserted, you will have to crank the engine for approximately five seconds and record the compression readings shown on the gage. Repeat the same procedure with each of the cylinders and compare the readings at the end.

Electronic Testing With an Engine Analyzer
In case of electronic testing, a computer operated analyzer is used to estimate the compression status of each cylinder. This is done by measuring the minor variations in engine cranking speed. Using the engine compression, a formula is fed in the machine. Being computer operated, it is relatively less time-consuming. You don't have to remove spark plugs, and you actually get a print out of the compression test readings, thus making comparison very easy.

Engine Compression Problem

Normal compression readings are assumed to be anywhere between 125 psi and 160 psi. A difference of 5 percent within the readings of all cylinders is normally allowed. Anything less or more than the normal readings will be subject to further scrutiny. Low compression ratings is basically a sign of cylinder malfunctioning. In this case, you will have to ideally go for further check up to a proper workshop. The problem may be anything ranging from a broken piston ring to burned exhaust valves. On the other hand, high compression ratings basically a sign of excessive carbon buildup in the engine.

Subjecting your vehicle to engine compression testing once in a while, is a healthy practice. Whether you do it on your own or get it done from a professional, it hardly matters. If you plan to do it yourself, you can refer to various engine compression charts for your vehicle model available online. As we have said earlier, the test is of great help in determining the various problems associated with vehicle engine, and if you don't remember when was the last time you went for it, now is the time.