HEAD GASKET TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)
In the tough to diagnose blown head gasket cases, a block test is the only way to confirm (or disprove) the problem.
Why didn't I start of with this test? Because TEST 1, TEST 2, and TEST 3 usually pinpoint a blown head gasket condition in about 95% of the cases (not to mention you don't have to spend any $$ to do them). It's the remaining hard to diagnose 5% percent where the effort of finding a block tester is worth it.
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 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.
You can buy one here:
Related Test Articles
There are several more ‘how to’ tutorials that I've written that are 2.2L Chevrolet: S10 Pick Up, Cavalier, Pontiac: Sunfire, GMC: Sonoma specific, that may be of further help. You can find them here: GM 2.2L Index Of Articles.
The following tutorials are samples of what you'll find in the index:
- How To Test The Manifold Absolute Pressure (MAP) Sensor (GM 2.2L).
- How To Test The Alternator (1994-1997 Chevy S10 2.2L).
- How To Test The Blower Motor Resistor (GM 2.2L).
- How To Do An Engine Compression Test (GM 2.0L, 2.2L, 2.5L).
- How To Test GM Ignition Coil Packs 2.2L Chevrolet Cavalier And Pontiac Sunfire (at: easyautodiagnostics.com).
If this info saved the day, buy me a beer!
