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

Block Tester To Check For A Blown Head Gasket. How To Test For A Blown Head Gasket (1991, 1992, 1993, 1994, 1995 2.5L Dodge Caravan And Plymouth Voyager)

I've seen some cases where a blown head gasket could not be pinpointed by the 3 previous tests. It took a block test to finally confirm that the head gasket was the one causing the engine to overheat.

So, if you're experiencing an engine that overheats as soon as you start it, I recommend doing a block test with a combustion leak detector.

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), combustion gases are entering the radiator. This result confirms a head gasket failure, a cracked block, or a cracked cylinder head issue.
  • If the blue chemical doesn't change color, you can conclude that you don't have a head gasket failure, a cracked block, or a cracked cylinder head issue.

You can shop for a block tester here:

More 2.5L Dodge Caravan And Plymouth Voyager Tutorials

There are several more 2.5L Dodge Caravan And 2.5L Plymouth Voyager specific 'how to' tutorials that I've written for your troubleshooting and diagnostic benefit. You can find them in this index: Chrysler 2.5L Index Of Articles.

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

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Dodge Vehicles:

  • Caravan 2.5L
    • 1991, 1992, 1993, 1994, 1995

Plymouth Vehicles:

  • Voyager 2.5L
    • 1991, 1992, 1993, 1994, 1995