TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)
It is not uncommon for certain head gasket failures not to cause any of the problems that the previous three tests attempt to confirm.
In these cases, the engine will start and run normally but will overheat immediately and the only way to pinpoint the overheating issue to a blown head gasket is to use a block tester on the engine.
In a nutshell, this is how the 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), 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?
To determine if the cylinder head is cracked, it must be removed from the engine block and subjected to a visual and/or pressure test. The pressure test is done at an automotive machine shop.
If the crack on the cylinder head is wide enough, you'll easily see it without a machine shop checking it.
If no cracks are visible to the naked eye, you still need to have it checked by a machine shop to be sure.
2.) How can I find out if the cylinder head is warped?
To determine if the cylinder head is warped, it must be removed from the engine.
After removal, the head sealing surface of the cylinder head must be absolutely clean. A precision straight-edge tool (along with feeler gauges) is then used to accurately measure the warpage.
If your vehicle is overheating and the head gasket has blown, you can bet the cylinder head is warped and needs to be resurfaced by a machine shop.
3.) Do I need to resurface the cylinder head?
The answer is YES! You should never reinstall the cylinder head without first having a machine shop pressure test and resurface the cylinder head (especially if the engine overheated).
More 3.0L Ford Ranger Tutorials
You can find a complete list of 3.0L V6 Ford Ranger tutorials here:
Here's a sample of the tutorials you'll find in the index:
- How To Test The Engine Compression (1991-2008 3.0L Ford Ranger).
- How To Test The Blower Motor (1998-2000 3.0L Ford Ranger).
- How To Test The Fuel Pump (1991-1994 3.0L V6 Ford Ranger) .
- How To Test The MAF Sensor (1998-2001 3.0L V6 Ford Ranger).
If this info saved the day, buy me a beer!
