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

Block Tester To Check For a Blown Head Gasket

There are times when one or both head gaskets get blown but the engine does not present any of the symptoms (like engine oil that looks like coffee with too much creamer etc.). This also means that the previous three tests did not confirm a blown head gasket and yet the engine overheats for no apparent reason.

In these cases the only way to confirm a blown head gasket problem is doing a block test with a block tester.

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 3.0L V6 Nissan Tutorials

You can find a complete list of tutorials in this index: Nissan 3.0L Index of Articles.

Here's a small sample of the 3.0L Nissan tutorials you'll find in the index:

  1. How To Test Engine Compression (3.0L Nissan).
  2. Mass Air Flow (MAF) Sensor Test 3.0L Nissan Quest (1993, 1994, 1995).
  3. Mass Air Flow (MAF) Sensor Test 3.0L Nissan Maxima (1995-1999).
  4. How To Test The Starter Motor (Nissan 3.0L, 3.3L) (at: troubleshootmyvehicle.com).
  5. How To Test Engine Compression (Nissan 3.0L, 3.3L, 3.5L) (at: troubleshootmyvehicle.com).
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