How To Test For A Blown Head Gasket (3.3L V6 Frontier, Pathfinder, Xterra)

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

The block test with a block tester is the test of choice when it comes to diagnosing a head gasket that causes the engine to overheat but that does not cause any other symptom (like engine oil that looks like coffee with too much creamer or engine coolant that shoots out of the opened radiator).

You'll need to run down to your auto parts store to rent or buy the block tester (you can also buy it online).

In a nutshell, this is how a block tester 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), then combustion gases are entering the radiator. This result confirms a blown head gasket, a cracked block, or a cracked cylinder head issue.
• If the blue chemical doesn't change color, then you can conclude that you don't have a blown head gasket, a cracked block, or a cracked cylinder head issue.

Where can you get the chemical and block tester? At your local auto parts store or here:

More Nissan 3.3L V6 Tutorials

If this tutorial was helpful, check out the others I've written for the 3.3L V6 equipped Nissan vehicles. You can find a complete list of tutorials here: Nissan 3.3L Index Of Articles.

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

• Mass Air Flow (MAF) Sensor Test 3.3L Frontier, Quest, Pathfinder, XTerra.
• How To Test The Camshaft Position Sensor (3.3L V6 Frontier, Quest, Pathfinder, Xterra) .
• Power Transistor Test And Ignition Coil Test 3.3L Nissan (1996-2004).
• Ignition System Wiring Diagram (1999-2004 3.3L Frontier And Xterra).