TEST 2: Coolant Shooting Out From Opened Radiator
The second most common symptom, of a blown head gasket, is coolant forcefully shooting out from an opened radiator.
Now even though your 3.5L V6 vehicle comes equipped with a radiator, there isn't a neck on it with a radiator cap that we can open.
Your Malibu comes equipped with a pressurized coolant reservoir (tank). It's to this coolant tank that we add coolant to the cooling system when needed.
This coolant tank's cap is the one that we have to remove to be able to perform this test.
IMPORTANT: Never open or remove the cap from the pressurized coolant reservoir if the engine is hot. If the engine has been running for any length of time, let it cool down completely. You can also cool down the engine in a matter of 15-20 minutes by placing a running box fan on top of it.
Let's get started:
- 1
Remove the coolant reservoir's cap. Check to see if there is coolant in it and if it's empty, add some water or coolant.
- 2
Crank the engine with the help of helper, while you stand at a safe distance from the open coolant tank.
- 3
You'll see one of two results:
1.) The water or coolant inside the opened coolant reservoir will shoot out.
2.) The coolant will not be disturbed. In other words, cranking the engine will have no effect on the level of the water or coolant in the resevoir.
Let's examine your test results:
CASE 1: Coolant shot out of the opened reservoir tank as you cranked the engine. This test result confirms that you have a blown head gasket on your 3.5L V6 engine.
The normal test result is for the coolant to not be disturbed as you crank the engine.
CASE 2: The coolant in the reservoir WAS NOT disturbed as you cranked the engine. This is the correct and expected test result.
If the engine in your vehicle is overheating and you have confirmed that the water pump, the radiator fans, the engine coolant thermostat are okay, then I suggest that you perform a chemical block test. For more info on this test go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
TEST 3: Engine Compression Test
NOTE: If the engine starts and runs but overheats then you can skip this test and go to TEST 4. This test step only applies if your 3.5L V6 engine is not starting.
In this section, we are going to see if the head gasket is causing the engine to not start.
If the head gasket is causing the engine to not start, it's usually because you have got at least 3 dead cylinders.
These are the test steps:
- 1
Remove all six spark plugs.
Disable the ignition system by disconnecting the ignition coil pack from its engine wiring harness connector. - 2
Thread in the compression tester by hand, on the first spark plug hole you're gonna' start with.
Do not use any tools to tighten the compression tester. Hand tightening the compression tester is more than enough to get the proper results. - 3
Have a helper crank the engine. The needle on the tester will climb, as the engine cranks, till the cylinder reaches its maximum compression. Once it stops climbing, have your helper stop cranking the engine.
On a piece of paper, write down the reading and what cylinder it belongs to (you can use the illustration above to help you identify the cylinder). Repeat the above steps in the remaining cylinders.
Let's examine your test results:
CASE 1: Your compression test results indicate that two or three cylinders have close to or 0 PSI compression. This test result confirms that the head gasket or head gaskets are blown only if the 'engine no-start' problem was preceded by a severe overheating problem.
If you want to find out more about how to interpret the engine compression test results you just obtained, check out this tutorial: How To Test The Engine Compression (2004-2010 3.5L V6 GM Engine).
CASE 2: The compression values of all 6 cylinders were similar. This is the correct and expected test result.
Your 3.5L V6 engine's no-start problem is not being caused by blown head gaskets.
