How To Test A Blown Head Gasket (3.4L V6 Buick, Oldsmobile)

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

Troubleshooting A Blown Head Gasket. Using A Chemical Block Tester (Combustion Leak Tester) (1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 3.4L V6 Buick Rendezvous, Oldsmobile Alero, Silhouette)

In some cases the engine has a head gasket failure, yet you're not going to see any of the three symptoms that the other three tests are designed to confirm as a blown head gasket.

To be a bit more specific, you're NOT going to see:

  • The engine oil mixed with coolant.
  • The coolant being shot out of the radiator as the engine is being cranked.
  • Two side-by-side cylinders with 0 PSI compression.

In these cases, the only way to find out if your engine has a blown head gasket failure, is to do a combustion leak tester test. This test is commonly known as a block test.

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:

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Buick Vehicles:

  • Rendezvous 3.4L
    • 2002, 2003, 2004, 2005

Oldsmobile Vehicles:

  • Alero 3.4L
    • 1999, 2000, 2001, 2002, 2003, 2004
  • Silhouette 3.4L
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004