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

Block Tester To Check For a Blown Head Gasket

If your Ram Pick Up is still overheating, but the previous 3 tests don't confirm a blown head gasket and you have:

  1. Verified the engine coolant thermostat is good.
  2. The fan clutch is good.
  3. Water pump is good.

Then there's a good chance you've got a blown head gasket in its initial stages. The way to find out is by doing a block test.

A block test is another name for a combustion leak detector test. And let me tell you, that a block test is the best way to find out if the head gasket is blown or not in those cases that the previous 3 tests cannot confirm or disconfirm a blown head gasket.

This is how this test 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.

You can shop for a block tester here:

Related Test Articles

There are several more 3.9L, 5.2L, 5.9L Dodge specific ‘How to Test’ articles that I've written for your troubleshooting and diagnostic benefit. To go there now, click here: Chrysler 3.9L, 5.2L, 5.9L Index of Articles.