How To Test For A Blown Head Gasket (1995-2000 1.6L Honda Civic)

If your Honda Civic has a blown head gasket, it'll do one of two things: over-heat or not start. Now, if you have already verified that the cooling system is full of coolant, that the water pump is working, and that both the thermostat and radiator fan motor(s) are working too, then your Honda Civic probably has a blown head gasket. This article will show you how to verify this with four different tests.

Two of the Honda Civic blown head gasket tests don't require any tools to do and can be done under 5 minutes. The third blown head gasket test requires a compression tester and fourth a block tester. All four are very easy to do and will effectively let you know the condition of the head gasket on your Civic.

ES You can find this tutorial in Spanish here: Cómo Probar El Empaque De La Cabeza (1.6L Honda Civic) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 1.6L Honda Civic: 1995, 1996, 1997, 1998, 1999, 2000.
• 1.6L Honda Civic Del Sol: 1994, 1995, 1996, 1997.

Engine Overheating Diagnostics: The following tutorials will help you troubleshoot the source of an engine overheating problem:

• Common Causes Of Engine Overheating (1995-2000 1.6L Honda Civic).
• How To Test The Radiator Fan Motor (1995-2000 1.6L Honda Civic).
• Radiator Fan Motor Switch Diagnostic Tests (1995-2000 1.6L Honda Civic).
• How To Bench-Test The Radiator Fan Relay (1996-2000 1.6L Honda Civic).
• How To Test The Thermostat (1995-2000 1.6L Honda Civic).

Symptoms Of A Blown Head Gasket

The most common cause of a blown head gasket is engine overheating, which usually happens because of one of these issues:

1. The radiator fan isn't working.
2. There's no coolant in the system due to a leak somewhere.
3. The thermostat is stuck closed and won't let coolant circulate.

When the head gasket gets blown on your Honda Civic, you'll notice one or more of the following symptoms:

• The engine is overheating, but you've already ruled out issues with the radiator fan or thermostat.
• White smoke is coming from the tailpipe, and it smells like antifreeze burning. This is a strong sign coolant is leaking into the combustion chambers.
• Your Civic's engine won't start, even though:
  • You've confirmed it's not an ignition system issue because there's spark at all the spark plug wires.
  • You've verified the fuel pump is delivering fuel to the injectors, so it's not a fuel issue.
• The engine oil looks thick and has a tan or off-white color. This can happen when coolant mixes with the oil, another sign of a blown head gasket.

HEAD GASKET TEST 1: Engine Oil The Color Of 'Coffee With Too Much Creamer'

This first test is a simple test and checks for one of the most common results of a blown head gasket on a Honda Civic which is coolant mixing with the engine oil.

In most cases, this is probably the only test you may have to do, to verify a blown head gasket, and not have to do the other two tests. But if this test doesn't conclusively verify a blown head gasket, then by all means proceed to the other two head gasket tests.

OK, I'll stop talking and we'll get this show on the road, this is what you need to do:

1. 1

   Open your Honda's hood.

2. 2

   Pull out the engine oil dipstick.

3. 3

   Check the condition of the engine oil sticking to the dipstick.

4. 4

   You're gonna' see one of two things:
   
   1.) The engine oil will be a creamy tan/off-white color.
   
   2.) The engine oil will be its usual normal color.

Alright, let's interpret the color of the engine oil:

CASE 1: The color of the oil is a light tan, like coffee with too much creamer. This result confirms that your Honda Civic's head gasket is blown.

If you're wondering why the oil looks like this? Well this is what happened:

1.) Your Honda Civic overheated to the point that the cylinder head warped (since it's made out of aluminum). This led to the head gasket to burn.

2.) Once the head gasket burns and the head warps, the head gasket is unable to keep engine oil, coolant, and compression/exhaust gases from mixing.

3.) This leads to the coolant entering the engine oil pan. As both of these mix, the result is an engine oil that is an off-white/tan color.

CASE 2: The color of the engine oil is normal. So far so good, but more testing is necessary to make sure the head gasket is not blown (especially if your Honda Civic is overheating or not starting), go to: HEAD GASKET TEST 2: Coolant Shooting Out From Open Radiator.

Here's the reason why: In about 90% of the times, a blown head gasket will cause the engine's coolant to mix with the oil, but not always. And so another test or tests are needed to either confirm a blown head gasket or exonerate the head gasket as blown. The next test is to see if the engine's compression/combustion gases are escaping thru' the radiator.

HEAD GASKET TEST 2: Coolant Shooting Out From Open Radiator

Another of the most common symptoms of a blown head gasket is the engine's compression or combustion gases entering the cooling system. This can easily be tested and in this test step, I'll show you how.

A word of caution: If your Honda Civic has been running for an extended amount of time, let the engine cool down for at least an hour, since this test step will ask you to remove the radiator cap. Be careful and remember that a radiator cap should never be removed from a hot radiator.

There's a good chance that your Honda Civic is not starting, in this case you don't have to worry about a hot engine.

1. 1

   Remove the radiator's cap.

2. 2

   Check to see if there is coolant in the radiator.
   
   If the radiator is empty, add some water or coolant to bring it up to the radiator's neck level.

3. 3

   Now, have a helper crank the engine while you stand at a safe distance from the open radiator.

4. 4

   You'll see one of two results:
   
   1.) The water or coolant inside the radiator will shoot up and out of the now open radiator.
   
   2.) The coolant will not be disturbed. In other words, cranking the engine will have no effect on the level of the water or coolant in the radiator.

OK, now that the testing part is done, let's take a look at what your results mean:

CASE 1: The coolant bubbled out or shot out from the radiator. This is a clear indication that the head gasket is blown.

This test result only happens when the head gasket has blown and/or the cylinder head has warped due to the engine overheating. No further testing is required.

CASE 2: The coolant DID NOT bubble out NOR shoot out from the radiator. This is the correct and expected test result.

If your Honda Civic cranks but does not start, your next step is to go to: HEAD GASKET TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).

If your Honda Civic starts and runs, but overheats for no apparent reason, go to: HEAD GASKET TEST 3: Engine Compression Test.

HEAD GASKET TEST 3: Engine Compression Test

What leads a lot of folks to misdiagnose a blown head gasket is that, in their particular case, they checked the engine oil and it was not mixed with coolant. They also did the radiator with the cap off test and the engine's compression or combustion gases were not escaping from there.

They never realized that a head gasket can get blown without causing the coolant to mix with the engine oil and without causing combustion gases from entering the cooling system. I have seen this enough to know that one more test has to be done.

How is this possible? Well, this happens because the head gasket has burned at a point between two cylinders (the image at the beginning of this tutorial shows this type of failure), the resulting gap in the head gasket will let only the compression/combustion of one cylinder to leak into the other and vice-versa, but nothing else (like coolant). If this happens, in a Honda Civic, this will cause a no-start condition.

This condition can be very easily verified by doing a compression test. In this test step, I'll show you how and more importantly, how to interpret the compression test results to see if the head gasket is burned or not.

These are the test steps:

1. 1

   Disable the ignition system. This will prevent spark from being created and delivered to the spark plug wires.
   
   You can do this by disconnecting the ignition coil's connector, if the ignition coil is located outside of the distributor on your Honda.
   
   If your Honda Civic has the ignition coil inside the distributor, disconnect the distributor's connectors, and this will disable the ignition coil.

2. 2

   Disconnect all four spark plug wires from their spark plugs.

3. 3

   Remove all of the spark plugs.

4. 4

   Thread in the compression tester by hand, on the first spark plug hole you're gonna' start with.
   
   Do not use any tools to tighten the compression tester. Hand tightening the compression tester is more than enough to get the proper results.

5. 5

   Have a helper crank the engine while you keep your eyes on the compression tester.
   
   The needle will climb, as the engine cranks, till it reaches the maximum cylinder compression.

6. 6

   At the point the gauge's needle stops climbing, have your helper stop cranking the engine.

7. 7

   On a piece of paper, write down the reading and what cylinder it belongs to. You can use the illustration above to help you identify the cylinder.

8. 8

   Repeat the above steps in the remaining 3 cylinders.

If your Honda Civic's head gasket is burned at a location between 2 cylinders, your compression test readings will give you 2 good compression readings and 2 compression readings that will be 0 PSI. Let me give you a more specific example:

Let's say that I tested my Honda Civic and I got the following cylinder compression readings:

• Cylinder #1 = 175 PSI
• Cylinder #2 = 165 PSI
• Cylinder #3 = 0 PSI
• Cylinder #4 = 0 PSI

As you can see from the above compression readings, cylinders #3 and #4 have 0 PSI readings. And this is a clear indication that the head gasket has burned at the point between them both. Now, in your specific case, you may not see those exact same cylinders with 0 PSI readings. It may be #1 and #2 or it may be #2 and #3, the main idea is that whatever cylinders are affected, they will always be side by side.

CASE 1: All cylinder compression readings where normal. These compression gauge readings confirm that the head gasket is OK and not burned at a point between two cylinders.

OK, 3 out of 3 tests have confirmed that the head gasket on your Honda Civic is not blown.

CASE 2: Two side by side cylinders had 0 PSI compression. This engine compression reading confirms that the head gasket is burned thru' at the point between those two cylinders. You'll need to replace the head gasket.

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

Sometimes, a blown head gasket doesn't want to reveal itself. In other words, the previous 3 tests just don't confirm a blown head gasket.

In these cases, the only way to make sure the head gasket is blown (or not) is by doing a block test.

This is how a combustion leak detector test (usually simply referred to as a block test) works:

• A blue liquid chemical, which is blue in color, is placed in the tester (see photo above).
• The tester assembly is then placed on the open radiator neck (you may have to drain some of the coolant in the radiator since this tool needs to 'gulp' some of the air inside the radiator).
• The rubber bellow is then squeezed to suck in the air up through the two fluid-filled chambers. As the air bubbles up through the fluid, it will cause a chemical reaction.
• If the blue chemical turns yellow (for gasoline engines), combustion gases are entering the radiator. This result confirms a head gasket failure, a cracked block, or a cracked cylinder head issue.
• If the blue chemical doesn't change color, you can conclude that you don't have a head gasket failure, a cracked block, or a cracked cylinder head issue.

You can shop for a block tester here:

More 1.6L Honda Civic Tutorials

There are several more 'how to' tutorials that I've written that are 1.6L Honda specific, that may be of further help. You can find the ones that are located here, at this site, by going to the 1.6L Honda Civic Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test Misfire Codes (1995-2000 1.6L Honda Civic).
• How To Test The Throttle Position Sensor (1995-2000 1.6L Honda Civic).
• How To Troubleshoot A No Start (1995-2000 1.6L Honda Civic).
• How To Test The Igniter, Ignition Coil (Accord, Civic, CRV, and Odyssey) (at: easyautodiagnostics.com).