How To Test For A Blown Head Gasket (1989-2001 3.9L V6 Dodge Ram Pickup)

There are 4 tests that are done to test for a blown head gasket. 2 of those 4 tests require no tools at all to perform.

In this tutorial, I'll explain how to do all 4 so that you can find out if your 3.9L equipped full-size Dodge Ram pickup has a blown head gasket (or not).

ES You can find this tutorial in Spanish here: Cómo Probar Los Empaques De Cabeza (3.9L V6 Dodge Ram Pickup y Van) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following Dodge Ram pickups:

• 3.9L V6 Dodge Ram 150 Pickup: 1989, 1990, 1991, 1992, 1993.
• 3.9L V6 Dodge Ram 250 Pickup: 1989, 1990, 1991, 1992, 1993.
• 3.9L V6 Dodge Ram 1500 Pickup: 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001.
• 3.9L V6 Dodge Ram 2500 Pickup: 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001.

NOTE: You can find all of the B-Series Ram van tutorials here:

• 3.9L V6 Dodge Ram Van Index Of Articles.

Symptoms Of A Blown Head Gasket

The most common cause of a blown head gasket is that the engine overheated because:

• Fan clutch failed.
• The engine ran without coolant (due to a coolant leak).
• Thermostat went bad and got stuck in its closed position and the coolant could not circulate.

The most common symptoms a blown head gasket are:

1. Your 3.9L V6 Dodge pickup is overheating. You know it's not the fan (or fan clutch) or thermostat.
2. White smoke is coming out of the tail-pipe and it smells like anti-freeze being cooked.
3. The engine does not start.
   • Your tests have confirmed that the ignition system is not behind the no-start problem.
   • Your tests have confirmed that the fuel pump is OK and not behind the no-start problem.
4. The engine oil is thick and tan to off-white color (mixed with coolant).

TEST 1: Oil The Color Of Coffee With Too Much Creamer

Generally, the most common end result of a blown head gasket is the engine oil mixed with coolant.

So for our first test, we'll check the condition and color of the oil sticking to the engine oil dipstick.

If the engine oil is the color of 'coffee with too much creamer', then you can conclude that one or both of the head gaskets, on your 3.9L V6 Dodge Ram pickup, are blown.

This is what you need to do:

1. 1

   Open the hood on your 3.9L pickup.

2. 2

   Pull out the engine's oil dipstick.

3. 3

   Check what the color of the oil is and how thick it is.

4. 4

   You'll see one of two things:
   
   1.) Either the oil on the dipstick is a creamy, off-white color and is thick as syrup.
   
   2.) The oil is its normal color and viscosity.

Let's examine your test result:

CASE 1: The engine oil looks like coffee with too much creamer. This test result tells you that one or both of the head gaskets are blown.

CASE 2: The color of the engine oil is normal. This is the correct and expected test result.

The next step is to check to see if compression/exhaust gases are leaking into the cooling system. Go to: TEST 2: Exhaust Gases Shooting Out Of The Radiator.

TEST 2: Exhaust Gases Shooting Out Of The Radiator

In this test, we're gonna' crank the engine with the radiator's cap removed.

If the coolant, inside the radiator, is shot out while cranking the engine, then you can conclude that one or both of the head gaskets are blown.

CAUTION: Do not remove the radiator cap with a hot engine! If the engine, in your Dodge pickup, has been running for any length of time, let it cool down completely before removing the cap from the radiator.

Let's get started:

1. 1

   Remove the radiator cap from the radiator.

2. 2

   Top off the radiator with water if the coolant level is low.

3. 3

   Have your helper to 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 result confirms a blown head gasket issue and lets you know that the combustion gases are leaking into the cooling system. No further testing is required.

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

If your 3.9L V6 Dodge pickup runs but runs with a misfire (or extreme rough idle), go to: TEST 3: Cylinder Compression Test.

If your 3.9L V6 Dodge pickup runs but starts to overheat immediately and for no apparent reason, go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).

TEST 3: Cylinder Compression Test

In some cases, the head gasket burns in a spot right between two side-by-side cylinders (you can see an example of this type of problem in the image at the very beginning of this tutorial).

In this cases, the engine usually starts and runs, but it runs with a misfire (or extreme rough idle).

The best way to diagnose this type of head gasket failure is with a compression test.

NOTE: You can find a more detailed explanation of how to do the compression test and how to interpret its results in this tutorial: How To Test The Engine Compression (1989-2001 3.9L V6 Dodge Ram Pickup).

OK, these are the test steps:

1. 1

   Disable the ignition system on your 3.9L V6 Dodge pickup.
   
   You can easily accomplish this by disconnecting the ignition coil's electrical connector.

2. 2

   Disable the fuel system.
   
   You can do this by disconnecting the fuel injectors' electrical connectors.

3. 3

   Disconnect all spark plug wires (from their spark plugs)
   
   NOTE: Before you disconnect them, label them with their cylinder number.

4. 4

   Remove all of the spark plugs.

5. 5

   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.

6. 6

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

7. 7

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

8. 8

   Write down the reading and what cylinder it belongs to (you can use the illustration above to help you identify the cylinder) on a piece of paper.

9. 9

   Remove the compression tester and repeat the above steps in the remaining cylinders.

OK, let's take a look at what your results mean:

CASE 1: All cylinder compression readings where normal. This is the correct test result and it confirms that both head gaskets are OK (not burned at a spot between two side-by-side cylinders).

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

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.

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

A blown head gasket can cause the engine to overheat within minutes of it starting but it won't present any of the other symptoms the previous 3 tests were checking for.

The only way to confirm that the problem is being caused by a blown head gasket is by doing a block test with a block tester.

A block test is another name for a combustion leak detector test. And let me tell you, that a block test is the best way to find out if the head gasket is blown or not in those cases that the previous 3 tests cannot confirm or disprove a blown head gasket.

This is how this 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 engine is cranked and started.
• 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 3.9L V6 Dodge Ram Pickup Tutorials

I've written quite a few 3.9L V6 Dodge Ram pickup 'how to test' tutorials. You can find them in this index:

• 3.9L V6 Dodge Ram Pickup Index Of Articles.

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

• How To Test The Engine Compression (1989-2001 3.9L V6 Dodge Ram Pickup).
• How To Test The Fuel Pump (1992-2001 3.9L V6 Dodge Ram Pickup).
• How To Test The TPS (1992-1996 3.9L V6 Dodge Ram Pickup).
• How To Test The MAP Sensor (1992-1996 3.9L V6 Dodge Ram Pickup).