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TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)
There are some cases where the previous three tests aren't able to confirm or exonerate a head gasket as blown.
In these cases your 3.9L Dodge Dakota's engine starts and runs but overheats for no apparent reason.
The surest way to find out if a blown head gasket is causing the engine to overheat is to do a block test with a block tester.
In a nutshell, this is how a block tester works:
- A blue liquid chemical, which is blue in color, is placed in the tester (see photo above).
- 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).
- 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 result 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 a cracked cylinder head issue.
Where can you get the chemical and block tester? At your local auto parts store or here:
20%$10.40
More 3.9L Dodge Dakota Tutorials
You can find a complete list of 3.9L Chrysler and Dodge tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- Testing The Ignition System (1998-2003 3.9L Dodge Dakota).
- How To Test The MAP Sensor (2000-2003 3.9L V6 Dodge Dakota).
- How To Test The TPS Sensor (2000-2003 3.9L V6 Dodge Dakota).
- How To Test The Crankshaft Position Sensor (1998-2003 3.9L Dodge Dakota).
- Engine Management Sensor Circuit Diagram (1994-1995 3.9L V6 Dodge Dakota).
If this info saved the day, buy me a beer!
