TEST 2: Exhaust Gases Shooting Out Of The Radiator
This second test is also a test that can be done under 5 minutes. But it has to be done with a completely cold engine.
What we'll be doing here is removing the radiator cap from the radiator and then cranking the engine to see if the coolant gets shot out.
If the coolant gets shot out of the radiator, while a helper is cranking the engine, then you can correctly conclude that one or both of the head gaskets are blown.
If the coolant remains undisturbed, then the next step is to go to TEST 3.
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:
- 1
Remove the radiator cap from the radiator.
If the radiator is not full, then top it off with water. - 2
Have your helper to crank the engine, while you stand at a safe distance from the open radiator.
- 3
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 3.1L V6 Buick (Oldsmobile), go to: TEST 3: Cylinder Compression Test.
If the engine, in your 3.1L V6 Buick (Oldsmobile), runs but overheats, go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
TEST 3: Cylinder Compression Test
Every now and then, a head gasket will fail and burn in a section right between two side-by-side cylinders. Matter fact, the photo at the beginning of this tutorial shows exactly that type of head gasket failure.
It's been my experience, that when this happens, the engine starts and runs but of course runs with a misfire problem.
The only way to diagnose this type of head gasket failure is to do a compression test.
NOTE: For a detailed explanation of the compression test and (especially) how to interpret your test results, take a look at this tutorial: How To Test Engine Compression (3.1L V6 Buick, Oldsmobile).
These are the compression test steps:
- 1
Disconnect the ignition coil from its electrical connector. This is will disable the ignition system and is an important safety precaution.
- 2
Disconnect the fuel pump relay from its electrical connector.
- 3
Disconnect all spark plug wires (from their spark plugs).
- 4
Remove all of the spark plugs.
- 5
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. - 6
Have a helper crank the engine as you observe the compression tester.
- 7
When the gauge's needle stops climbing, have your assistant stop cranking the engine.
- 8
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).
- 9
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.
