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How to Perform a Compression Test on the Engine in a Toyota Camry

by Contributor

The Toyota Camry originally came with a 4-cylinder engine but soon offered the choice of a V6 engine. When the car loses power, burns oil or runs poorly, a simple compression test can diagnose the cause. Parts inside the engine wear out over time, and a compression test allows you to see what is happening inside of the engine without going to the trouble of tearing it apart.

Warm up the engine in the Toyota Camry before performing the compression test since running one on a cold engine produces inaccurate results. Make sure that the battery is in good condition, since it will need to spin the engine several times.

Disable the ignition system to avoid electrical shock during the test. Remove all of the spark plugs and check each one for damage, since it is a sign of damage within the cylinder. If the Toyota Camry contains a 4-cylinder engine, there will be four spark plugs, but if it has a V6, there will be six.

Insert the compression tester into one of the spark plug holes. Crank the starter to rotate the engine and build compression within the cylinder. Write down the compression number for that cylinder.

Repeat the test on all of the cylinders, keeping a record of the compression numbers. Compare them to each other. They should be similar and fall within 10 PSI of each other.

Compare the compression numbers to the recommended compression ratio. If the Toyota Camry contains a 3.5L or 3.3L V6 engine, the compression ratio is 10.8:1. If it has a 3.0L V6 engine, the ratio is 10.5:1. The compression numbers should fall within 15 PSI of the compression ratio.

Add a small amount of motor oil to any cylinders that have a low compression number and perform the compression test again. If the number increases, the cylinder was worn walls or piston rings, but if it remains the same, there are worn valves or valve seats within the cylinder instead.

Tips

  • If the engine is a 4-cylinder, the ratio varies by year. From 1994 to 2001, it is 9.5:1. From 2002 to 2006, the ratio is 9.6:1 and from 2007 to 2009, the correct ratio is 9.8:1.
  • The compression ratios for models earlier than 1994 vary, so check the vehicle manual for the recommended ratio.

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