TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)
Professional repair shops have always relied on a block tester to find out if there are any head gasket issues causing the vehicle to overheat (after performing the previous tests).
If, in your particular situation, you're face with a deep suspicion that one of the 2 (or both) head gaskets is blown but the 3 previous tests don't pinpoint it, your next step is to do a chemical block test.
In a nutshell this is how the test 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 engine is started.
- 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.
Where can you get the chemical and block tester? You can buy here:
Related Test Articles
There are several more GM 4.3L, 5.0L and 5.7L specific 'how to' tutorials that I've written for your troubleshooting and diagnostic benefit. The articles that are here in this web site, you can find them here:
If you need to test the ignition system (like the ignition module, ignition coil, distributor cap, spark plug wires), you can find the step-by-step tests in the following two test articles (found at easyautodiagnostics.com).
- How To Test A Misfire / No Spark-No Start Condition GM 4.3L, 5.0L, 5.7L Distributor Ignition System (1996-2004) (at: easyautodiagnostics.com).
- This article will help you to find the cause of a misfire or 'no-spark no-start' condition on your GM car, Pick Up, mini-van, van or SUV equipped with a 4.3L, or 5.0L, or 5.7L engine. The testing is explained step by step, making the whole diagnostic and troubleshooting as pain free as possible.
- How To Test GM Ignition Control Module 4.3L V6, 5.0L V8, and 5.7L V8 (1995 thru' 2005) (at: easyautodiagnostics.com).
- This is one of the easiest GM ignition control modules to test. This article will take you step by step through the whole process of diagnosing and troubleshooting a bad ignition control module and ignition coil.
If this info saved the day, buy me a beer!
