Blown Head Gasket Tests (2004-2006 2.8L Chevrolet Colorado, GMC Canyon)

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

Some blown head gasket cases are difficult to diagnose with the previous three test methods.

The only way to confirm the engine has suffered a blown head gasket, in these cases, is by performing a block test on the engine with a combustion leak detector.

This is how the combustion leak detector test (block test) works:

• The combustion leak detector tester is filled with a blue liquid chemical (see photo above).
• The radiator cap is removed (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 started.
• The tester is then placed on the open radiator neck.
• 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 in turn 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 cracked cylinder head issue.

You can shop for a block tester here:

More 2.8L Chevrolet Colorado (GMC Canyon) Tutorials

You can find a complete list of 2.8L Chevrolet Colorado (GMC Canyon) tutorials and wiring diagrams here:

• GM 2.8L Vortec 4-Cylinder Index of Articles.

Here's a list of articles you'll find there:

• How To Test The Electronic Throttle Body (2004-2006 2.8L Chevrolet Colorado, GMC Canyon).
• How To Test Engine Compression (2004-2006 2.8L Chevrolet Colorado, GMC Canyon).
• APP Sensor Tests (2004-2006 2.8L Chevrolet Colorado, GMC Canyon).
• TAC Throttle Body Wiring Diagram (2004-2006 2.8L Chevrolet Colorado, GMC Canyon).