TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)
Every now and then, a blown head gasket problem doesn't show any of the symptoms the prior 3 tests are checking for yet your Isuzu continues to overheat. In these tough to diagnose cases, the only way to confirm (or disprove) a blown head gasket is by doing a block test with a chemical block tester.
The combustion leak tester (or block tester) test is so effective that it's used in all major/competent repair shops to confirm a blown head gasket issue.
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 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? Here:
20%Frequently Asked Questions
1.) How can I tell if the cylinder head is cracked?
The only way to know is to remove the cylinder head and visually inspect it. If the crack is wide enough, you'll be able to easily see it.
In many instances, a visual inspection won't be enough and you'll need to have the machine shop (that's gonna' resurface the cylinder head) perform a pressure test on the cylinder head.
2.) Do I need to resurface the cylinder head?
The answer is YES! You should never reinstall the cylinder head or cylinder heads without first having a Machine Shop resurface the cylinders heads (particularly over an overheating condition).
Now, of course, if you (or the machine) have checked it with a straight-edge and there's no warpage then and only then is the cylinder head not resurfaced.
Related Test Articles
You'll find a complete list of How To test articles for the 2.6L Isuzu vehicles in here: Isuzu 2.6L Index Of Articles.
Here's a small sample of the articles, you'll find:
- Engine Compression Test.
- How To Test The Throttle Valve (TV) Switch (2.6L Isuzu).
- Under Hood Fuse/Relay Box (1990-1994 Isuzu 2.6L).
- MAF Sensor Test.
- Starter Motor Bench Test.
If this info saved the day, buy me a beer!
