How to Test Compression in Mitsubishi Engines


Since it entered the market, the engine in the Mitsubishi has changed many times. Regardless of whether the car is a four-cylinder or V-6 engine, it is crucial that you keep it running properly. Parts wear out over time, which can cause the engine to burn oil. A simple compression test is an inexpensive way of determining problems in the engine without damaging the engine.

Things You'll Need

  • Compression tester
  • Motor oil
  • Warm up the engine in your Mitsubishi. Running a compression test on a cold engine will not produce accurate findings. Ensure that the battery is in good shape, as you will need it to spin the engine multiple times during the test.

  • Remove the spark plugs from the engine, and disable the ignition system to prevent electrical shock. If the car has a four-cylinder engine, there will be four spark plugs (a V-6 will have six spark plugs). By removing the spark plugs, the engine will now spin unhindered.

  • Put the compression tester in one of the spark plug holes and then crank the starter. This prompts rotation of the engine and will consequently build compression in the cylinder. Write down the compression number and move on with each spark plug hole. Record all of the compression figures.

  • Compare the compression numbers you wrote down to the recommended Mitsubishi compression ratios.

  • Analyze the compression numbers to make certain that they are within 10 PSI of each other. Perform the test again on any cylinder with a low reading after adding a little bit of motor oil to that cylinder. If the new compression number reading increases, this is indicative of worn piston rings or cylinder walls. If the number does not change, the problem lies in worn valves or valve seats.

Tips & Warnings

  • Compression numbers should always be within 15 PSI of the numbers recommended in your owner's manual.

Related Searches


  • "Mitsubishi: Eclipse 1990-98"; Chilton; 1998
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