TEST 2: Exhaust Gases Shooting Out Of The Radiator
This 2nd test is an easy one to do also. It only involves removing the radiator cap from the radiator and then cranking the engine.
What we're looking for is if the coolant, inside the radiator, gets shot out while you're cranking the engine.
If the coolant does get shot out of the radiator, then you can conclude that you've got a blown head gasket on your hands.
If the coolant remains undisturbed, which is the correct and expected result, then you can move on to the next test.
CAUTION: Do not remove the radiator cap from the radiator if the engine is hot. If the engine has been running for any length of time, then let it cool down completely before removing the radiator cap!
These are the test steps:
Remove the radiator cap from the radiator.
If the radiator is not full, then top it off with water.
Have your helper to crank the engine, while you stand at a safe distance from the open radiator.
You'll see one of two results:
1.) The water or coolant inside the radiator will shoot up and out of the now open radiator.
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 radiator.
Let's examine your test result:
CASE 1: The coolant bubbled out or shot out from the radiator as the engine was cranked. This result confirms that one or both of the head gaskets are blown.
CASE 2: The coolant DID NOT bubble out NOR shoot out from the radiator as the engine was cranked. This is the correct test result.
If the engine doesn't start, in your 3.4L V6 Buick (Oldsmobile), go to: TEST 3: Cylinder Compression Test.
If the engine, in your 3.4L V6 Buick (Oldsmobile), runs but overheats, go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
TEST 3: Cylinder Compression Test
If you take a look at the photo at the beginning of this tutorial, you'll notice that the head gasket burned in a section between two side-by-side cylinders.
Although this doesn't happen very often, it does happen. When it does, you'll have two side-by-side cylinders with 0 compression.
The only way to check for this type of head gasket failure is to do a compression test. That is what we'll do in this test section.
NOTE: You can find the engine compression test and how to interpret its results explained in more detail here: How To Test The Engine Compression (3.4L V6 Buick, Oldsmobile).
OK, let's get started:
Disconnect the ignition coil/ignition control module assembly from its electrical connectors. This is will disable the ignition system and is an important safety precaution.
Disconnect the fuel pump relay from its electrical connector.
Disconnect all spark plug wires (from their spark plugs).
Remove all of the spark plugs.
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.
Have a helper crank the engine as you observe the compression tester.
When the gauge's needle stops climbing, have your assistant stop cranking the engine.
Write down the reading and what cylinder it belongs to on a piece of paper (you can use the illustration above to help you identify the cylinder).
Remove the compression tester and repeat the above steps in the remaining cylinders.
OK, let's take a look at what your results mean:
CASE 1: All cylinder compression readings where normal. This is the correct test result and it confirms that the head gaskets are OK (not burned at a spot between two side-by-side cylinders).
If you still suspect a blown head gasket, go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
CASE 2: Two side by side cylinders had 0 PSI compression. This test result confirms that the head gasket is burned thru' at the point between those two cylinders. You will need to replace both head gaskets.