TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)
In some cases when the head gasket fails, you're not going to see the engine oil mixed with engine coolant (TEST 1) and you're not going to see the coolant being shot out of the pressurized coolant tank or coolant filler neck (TEST 2).
What you will see is that the engine starts and runs but it seems to overheat for no reason.
In these cases the only way to find out if one or both of the head gaskets are causing the problem is to do a chemical block test.
You can buy a block tester in just about any auto parts store. 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 coolant filler neck or coolant tank (you may have to drain some of the coolant in the radiator since this tool needs to ‘gulp’ some of the air inside the coolant filler neck or coolant tank).
- 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 thus confirming a head gasket, a cracked blocked, or cracked cylinder head issue.
- 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 3.9L V6 Test Tutorials
You can find a complete list of 3.9L V6 diagnostic test tutorials here: GM 3.9L Index Of Articles.
Here's a list of articles you'll find there:
- How To Test The Engine Compression (2006-2010 3.9L V6 Engine).
- Ignition System Wiring Diagram (2006-2009 3.9L Chevrolet Impala).
- Ignition System Wiring Diagram (2006-2007 3.9L Chevrolet Malibu).
- How Often Should I Replace The Spark Plugs (2006-2010 3.9L V6 Engine).
If this info really saved the day, buy me a beer!