TEST 2: Coolant Shooting Out From Open Radiator
Another very common test, to see if there's a head gasket failure present, is to see if engine coolant will shoot out of radiator (with cap removed) while the engine is cranked.
If the engine coolant shoots out of the radiator, while then engine is cranked, then you can conclude that the head gasket is blown on your 2.7L V6 Honda Accord.
IMPORTANT: Do not remove the radiator cap from the radiator if the engine is hot or has been running for any length of time. If the engine is hot then let it cool down completely before removing the cap from the radiator.
These are the test steps.
- 1
Remove the radiator's cap.
Check the coolant level in the radiator. If the radiator is empty then add some water or coolant. - 2
Have your helper 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 out of the open radiator.
2.) The coolant remained undisturbed. 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 shot out from the radiator as you cranked the engine. This confirms that the head gasket is blown on your 2.7L Honda Accord.
CASE 2: The coolant DID NOT shoot out from the radiator. This is the correct and expected test result.
If the engine, in your 2.7L V6 Honda Accord, starts but runs with a misfire, then next step is to test engine compression. For this test go to: TEST 3: Engine Compression Test.
If the engine starts but overheats almost immediately, then your next step is to do a 'block' test. For this test go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
TEST 3: Engine Compression Test
There are cases where the head gasket burns in a section right between two cylinders (like the head gasket shown in the photo at the beginning of this tutorial).
When this happens, the engine will not start because two side by side cylinders will produce no compression.
This type of head gasket failure can by confirmed by doing a cylinder compression test and that's what we'll do in this section.
These are the test steps:
- 1
Disable the ignition system by disconnecting the ignition coil from its engine wiring harness connector.
- 2
Remove all of the spark plugs.
- 3
Install the compression tester by hand in the spark plug hole of cylinder #1.
Do not use any tools to tighten the compression tester. Hand tightening the compression tester is more than enough to get the proper results. - 4
Have your helper crank the engine.
The needle on the tester will climb as the engine cranks. Once the cylinder reaches its maximum compression the needle will stop climbing.
Once it stops climbing have your helper stop cranking the engine. - 5
Write down the reading and what cylinder it belongs to (you can use the illustration above to help you identify the cylinder).
- 6
Repeat steps 2 through 5 in the remaining cylinders.
Let's take a look at what your test results mean:
CASE 1: All cylinder compression readings were above 0 PSI. This is the correct and expected test result.
Your next step is to perform a block test with a block tester. For this test go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
CASE 2: Two side by side cylinders had 0 PSI compression. This engine compression test result confirms that the head gasket (of that bank of cylinders) is burned at the point between those two cylinders. You'll need to replace the head gasket.
