How To Test For A Blown Head Gasket (1992-1995 1.5L Honda Civic)

When your 1.5L Honda Civic overheats and the head gasket gets blown, you'll see some very specific symptoms. It's these symptoms, that will confirm the head gasket is blown.

In this tutorial, I'll show you the 4 most common tests done to check for a blown head gasket.

Two of these tests don't require any tools whatsoever and can be done under 5 minutes. For the third test, you'll need a compression tester and the fourth test is done with a block tester.

You can find this tutorial in Spanish here: Cómo Verificar un Empaque de Cabeza Quemado (1.5L Honda Civic) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 1.5L Honda Civic: 1992, 1993, 1994, 1995.

ENGINE NO-START DIAGNOSTICS: Troubleshooting an engine no-start problem? If the head gasket checks out fine, the guide below will walk you through diagnosing and engine no-start step by step:

• How To Troubleshoot A No Start (1992-1995 1.5L Honda Civic).

Symptoms Of A Blown Head Gasket

There are several symptoms, that you'll see when the head gasket gets blown on your 1.5L Honda Civic. Depending on how bad the head gasket is, your Civic will either not start or start and overheat.

Here's a basic list of what you may see if your Civic has a blown head gasket:

1. Overheating.
2. Oil mixed with coolant.
3. White smoke coming out of the tail-pipe.
4. Engine cranks, but does not start.
5. No compression on two adjacent cylinders.
6. Coolant being pushed forcibly into the coolant reservoir bottle whenever the engine idles or the engine is turned off.

If your 1.5L Honda Civic starts and runs, but overheats and you have already checked and confirmed that the water pump, the thermostat, the radiator fan motors are OK, then there's a good chance you have a blown head gasket on your hands. The following 4 tests will help find out.

TEST 1: Engine Oil Mixed With Coolant

Whenever I was given a 'car overheats, possible blown head gasket' or a 'car doesn't start after overheating' to diagnose, the first thing I would do was check to see if the car's engine oil was mixed with coolant.

Why? Because this is usually the most common end-result of a blown head gasket. In my personal experience, about 90% of the vehicles diagnosed with a bonafide blown head gasket had this 'engine oil mixed with coolant' condition.

This is a very easy and simple test. This is what you have to do:

1. 1

   Open the hood of the car.

2. 2

   Pull out the engine oil dipstick.

3. 3

   Check the color of the oil sticking to the dipstick.

4. 4

   You'll see one of two things:
   
   1.) The color of the oil will be a milky white color (like coffee with too much cream).
   
   2.) The color of the oil will be its normal color.

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

CASE 1: The engine oil was a milky white color. This tells you that the coolant is mixing with the engine oil as a result of a blown head gasket.

CASE 2: The engine oil was its normal color. So far so good.

You're not out of the woods yet, your next step is to see if the head gasket is leaking cylinder compression pressure into the cooling system. For this test go to: TEST 2: Coolant Shooting Out Of Radiator.

TEST 2: Coolant Shooting Out Of Radiator

After quickly checking the color of the oil, the next test was to see if coolant would shoot out of the radiator (with the cap removed) when cranking the engine.

The idea behind this test was to see if the head gasket was blown and letting compression pressures escape thru' the cooling system (which the radiator is a major component of).

This test checks for the second most common end-result of a blown head gasket and it's the next one I'm gonna' suggest to you.

OK, these are the test steps:

1. 1

   Remove the radiator cap from the radiator.
   
   If the coolant level is low, top it off before proceeding.
   
   IMPORTANT: The engine should be completely cold before you open the radiator cap. Opening the radiator cap on a hot engine can spray hot coolant all over you and severely burn you.

2. 2

   Stand at a safe distance from the engine but within view of the radiator.

3. 3

   When ready, have your helper crank the engine.

4. 4

   You'll see one of two results:
   
   1.) The coolant shoots out violently when the engine is cranked.
   
   2.) The coolant is not disturbed at all.

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

CASE 1: The coolant shot out of the radiator. This confirms beyond a shadow of a doubt that you do have a blown head gasket on your hands.

CASE 2: The coolant DID NOT shoot out of the radiator. So far so good. In TEST 1, you confirmed that coolant isn't mixing with the engine oil. In this test you have confirmed that no exhaust gases are escaping thru' the radiator.

OK, your next step comes down to two possibilities:

• If the engine doesn't start, your next step is to go to: TEST 3: Engine Compression Test.
• If the engine starts and runs, but overheats within minutes for no apparent reason, your next step is: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).

TEST 3: Engine Compression Test

It doesn't happen very often, but every now and then a head gasket gets burned in the spot right between two adjacent cylinders. This results in the compression of one cylinder to escape into the other and vice-versa.

The end result of this condition was an engine that cranks but doesn't start. The way to check this by doing a compression test and it's the 3rd test I'm gonna' recommend you do.

NOTE: You can find a more detailed explanation of how to do the compression test and interpret its results here: How To Test Engine Compression (1992-1995 1.5L Honda Civic).

Alright, let's get to it:

1. 1

   Disable the fuel system and the ignition system.

2. 2

   Disconnect the spark plugs wires from the spark plugs.

3. 3

   Remove the spark plugs.

4. 4

   Install the compression tester (hand tight only) on the first cylinder you're gonna' test.

5. 5

   Have a helper crank the engine while you observe the compression tester.

6. 6

   When the needle stops moving, have your helper stop cranking the engine.

7. 7

   Write down the compression readings.

8. 8

   Repeat on the next 3 cylinders.

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

CASE 1: You got 2 side by side (adjacent) cylinders with 0 PSI. This confirms beyond a shadow of a doubt that you do have a blown head gasket on your hands.

CASE 2: All cylinders had sufficient compression. This is the correct and expected test result.

If you still suspect that your vehicle has a blown head gasket, go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).

TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)

When the first three tests don't give you a clear answer, using a combustion leak detector (commonly called a block tester) is the most reliable way to confirm whether the head gasket is blown.

Here's how the test is done:

• A special test fluid (blue in color) is poured into the tester (see photo above).
• The tester is then fitted to the radiator's open neck. In some cases, you'll need to lower the coolant level a bit since the tool has to draw in some of the radiator's air.
• Start up the engine.
• Squeeze the rubber bulb so it pulls air through the two chambers filled with the test fluid. As the bubbles move through, they trigger a chemical reaction.
• If the blue fluid changes to yellow (on gasoline engines), it means combustion gases are leaking into the cooling system. That's a sure sign of a blown head gasket, cracked head, or cracked block.
• If the fluid stays blue, you can rule out a blown head gasket, cracked block, or cracked cylinder head.

You can pick up a block tester here:

Frequently Asked Questions

1.)  How can I tell if the cylinder head is cracked?

The cylinder head has to be removed and visually inspected. If the crack is wide enough, you'll be able to easily see it.

Sometimes, a visual inspection proves inconclusive, this is why it's important to let a machine shop pressure test it for you.

2.)  Do I need to resurface the cylinder head?

YES, you need to resurface the cylinder head! You should never reinstall the cylinder head or cylinder heads without first having a Machine Shop resurface the cylinders heads (particularly over an overheating condition).

Now, of course, if you (or the machine) have checked it with a straight-edge and there's no warpage, then and only then is the cylinder head not resurfaced.