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

  • By: Abraham Torres-Arredondo
  • Created: 15 November 2021
  • Updated: 17 February 2024
  • Articl Id: 1047
Page 3 of 3

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:

UView 560000 Combustion Leak Tester
UView 560000 Combustion Leak Tester
OEMTOOLS 27145 Combustion Leak Detector, Plastic and Rubber Tester for Engine Block Leaks, Automotive Blown Head Gasket Test
OEMTOOLS 27145 Combustion Leak Detector, Plastic and Rubber Tester for Engine Block Leaks, Automotive Blown Head Gasket Test
Lisle 75630 Test Fluid
Lisle 75630 Test Fluid

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  2. Applies To:

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