How to Do a Compression Test
Bring the engine to its normal running temperature., Switch off the engine completely before beginning the test. , Remove the fuel pump relay., Disconnect the electrical connection from the ignition coil pack., Disconnect the wires for each spark...
Step-by-Step Guide
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Step 1: Bring the engine to its normal running temperature.
This can be done in the following ways.
If you haven't driven your car recently then the engine is most likely cold.
Start your vehicle as usual and keep the engine running for a few minutes.
This should warm up the engine to its normal operating temperature; however you should be careful not to overheat the engine by keeping it started for too long.
Usually keeping the engine started for 20 minutes is sufficient.
Turn off the car engine and allow the engine to cool if you have recently taken your car for a drive.
If the engine is hot, it should be given approximately 1 hour to rest before you do a compression test on it.
If you can't start the car engine then just continue with the test anyway.
Even though you won't be able to test the engine's performance accurately you will still be able to diagnose that the engine is faulty due to its internal compression if you get a low reading. -
Step 2: Switch off the engine completely before beginning the test.
, This will disable the fuel system so fuel will not be injected into the cylinders. , This will disable the ignition system since the ignition coil pack will be unable to create and distribute the spark from the spark plug. , Handle the spark plugs cautiously since the ceramic insulator of a spark plug can break or malfunction if not handled delicately. , Don't use any additional tools to tighten the compression gauge, you should only use hand force. , The needle on the pressure gauge will rise and once the needle has risen to its maximum reading your helper should stop the engine.
This maximum reading is the maximum compression value for the first cylinder that you have just tested. , -
Step 3: Remove the fuel pump relay.
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Step 4: Disconnect the electrical connection from the ignition coil pack.
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Step 5: Disconnect the wires for each spark plug then remove the spark plugs.
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Step 6: Put the engine compression gauge into the first cylinder's spark plug hole (this is the hole that is nearest to the drive belt).
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Step 7: Ask a helper to crank the engine over continuously.
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Step 8: Repeat the engine compression test for the other cylinders until you have tested all of the cylinders on your engine.
Detailed Guide
This can be done in the following ways.
If you haven't driven your car recently then the engine is most likely cold.
Start your vehicle as usual and keep the engine running for a few minutes.
This should warm up the engine to its normal operating temperature; however you should be careful not to overheat the engine by keeping it started for too long.
Usually keeping the engine started for 20 minutes is sufficient.
Turn off the car engine and allow the engine to cool if you have recently taken your car for a drive.
If the engine is hot, it should be given approximately 1 hour to rest before you do a compression test on it.
If you can't start the car engine then just continue with the test anyway.
Even though you won't be able to test the engine's performance accurately you will still be able to diagnose that the engine is faulty due to its internal compression if you get a low reading.
, This will disable the fuel system so fuel will not be injected into the cylinders. , This will disable the ignition system since the ignition coil pack will be unable to create and distribute the spark from the spark plug. , Handle the spark plugs cautiously since the ceramic insulator of a spark plug can break or malfunction if not handled delicately. , Don't use any additional tools to tighten the compression gauge, you should only use hand force. , The needle on the pressure gauge will rise and once the needle has risen to its maximum reading your helper should stop the engine.
This maximum reading is the maximum compression value for the first cylinder that you have just tested. ,
About the Author
Amy Diaz
Creates helpful guides on crafts to inspire and educate readers.
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