How To Test Engine Compression (1.5L Toyota Tercel)

The engine compression test can tell you quite a lot about the engine's internal condition, and the cool thing is that doing a compression test on the 1.5L Toyota Tercel engine is easy!

What makes the compression test on the 1.5L Toyota Tercel so easy is that the spark plugs (which have to be removed) are very accessible.

In this tutorial, I'll show you how to do the test and, more importantly, how to interpret your test results.

En Español You can find this tutorial in Spanish here: Cómo Probar La Compresión Del Motor (1.5L Toyota Tercel) (at: autotecnico-online.com).

Important Tips And Suggestions

TIP 1: You'll be working around a cranking engine, so be careful and stay alert at all times. Use common sense and think safety all of the time.

TIP 2: To test the engine's compression, you'll need to remove all four spark plugs. You should never remove the spark plugs from a hot engine. If the engine has been running for any length of time, let it cool down completely.

Why? The spark plug threads in the cylinder head can easily get damaged (as in getting stripped), and this is a nightmare you do not want to experience.

Which Compression Tester Should I Buy?

There are lot of engine compression testers to choose from and many places to buy them. I'm gonna' make two recommendations to you:

1) Which one to buy:  The engine compression tester that I have always used is the Actron CP7827 Compression Tester Kit. My only complaint about this engine compression tester is that it does not come with a case to store it in.

Engine Compression Gauge Testers

2) Where to buy:  You can buy an engine compression tester just about anywhere, but you'll end up paying more for it (especially at your local auto parts store). The above links will help you comparison shop. I think you'll agree it's the better way to save money on the compression tester!

TEST 1: Dry Compression Test

How To Test Engine Compression (1.5L Toyota Tercel)

To get this show on the road, we're gonna remove all of the spark plugs.

Once removed, we'll test the compression of all four cylinders.

Once you've gotten all four compression readings, we're gonna do some math to find out if any of those compression readings are causing a problem.

OK, to get started this is what you'll need to do:

  1. 1

    Remove the spark plugs.

    When removing the spark plugs, be careful not to drop any of them on the floor, or you run the risk of having the spark plugs porcelain insulator crack and then you'll have a misfire on your hands.

  2. 2

    Disable the fuel system by removing the fuel pump fuse. Disabling the fuel system will prevent fuel from being injected into each cylinder when the test is performed.

  3. 3

    Thread the engine compression gauge into the spark plug hole for the number 1 engine cylinder. Hand tighten the compression gauge only! Do not use any type of tool to get it tight.

  4. 4

    Have your helper crank the engine as you observe the needle on the compression gauge.

  5. 5

    Have your helper stop cranking the engine once the the needle (on the compression gauge) stops climbing.

  6. 6

    Write the value down and repeat this test step on the remaining 3 cylinders.

Let's take a look at what your test results mean:

CASE 1: 0 PSI on all four cylinders. This test result tells you that a serious internal mechanical problem is causing the engine to not produce compression.

The most common cause of 0 PSI compression in all four cylinders is:

  • A timing belt problem.
  • A blown head gasket.
  • A blown engine.

Any compression value below 100 PSI (even if it does not 0 PSI) means internal mechanical engine trouble.

CASE 2: Low compression in one or more cylinders. It's not unusual for each cylinder's compression to vary slightly different from one another (especially in high mileage engines).

If the compression values vary too much then you'll have an engine performance problem. The cool thing is that we can find out if the variations in the values, you wrote down, indicate a problem (with that cylinder) or not. Go to: Interpreting Your Compression Test Results.