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

Block Tester To Check For a Blown Head Gasket

Using a block tester, to check for a blown head gasket when the previous 3 tests don't confirm it, will tell you without a shadow of doubt if it's blown or not.

Why didn't I start of with this test? Because TEST 1, TEST 2, and TEST 3 usually pin-point a blown head gasket condition in about 95% of the cases (not to mention you don't have to spend any $$ to do them). It's the remaining hard to diagnose 5% percent where the effort of finding a block tester is worth it.

In a nutshell, this is how a block tester works:

  1. A blue liquid chemical, which is blue in color, is placed in the tester (see photo above).
  2. 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).
  3. 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.
  4. If the blue chemical turns yellow (for gasoline engines)... then combustion gases are entering the radiator thus confirming a head gasket, a cracked blocked, or cracked cylinder head issue.
  5. If the blue chemical doesn't change color, then you can conclude that you don't a head gasket, a cracked blocked, or cracked cylinder head issue.

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

More Honda Civic Test Tutorials

You can find a complete list of Honda Civic tutorials in this index: Honda 1.7L Index of Articles.

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

  1. How To Test The Crank Sensor (2001-2005 1.7L Honda Civic).
  2. Maintenance Required Light Reset (2001-05 1.7L Honda Civic).
  3. How To Do A Cylinder Balance Test (2001-2005 1.7L Honda).
  4. How To Test Trouble Code P0141 (2001-2005 Honda 1.7L).
  5. How To Test The TP Sensor (2001-2005 Honda 1.7L).
  6. How To Test Trouble Code P0135 (2001-2003 Honda 1.7L).