TEST 2: Coolant Shooting Out From Open Radiator
The next most common end result of a blown head gasket is coolant shooting out of the opened radiator as the engine cranks.
This happens when one or both of the head gaskets fail and allow cylinder compression to escape in to the engine's cooling system.
For this test you have to remove the radiator cap from the radiator. Once removed, the engine has to be cranked.
The normal test result is for the engine coolant to remain undisturbed as the engine is cranked.
If the engine coolant is forcefully shot out of the opened radiator then you can conclude that one or both of the head gaskets are blown.
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 one or both of the head gaskets are blown on your 3.0L V6 Nissan Pathfinder (D21 or Pick Up).
CASE 2: The coolant DID NOT shoot out from the radiator. This is the correct and expected test result.
If the engine runs with a misfire or a rough idle, your next step is to test the engine compression on your 3.0L V6 Nissan Pathfinder (D21 or Pickup). For this test go to: TEST 3: Engine Compression Test.
If the engine overheats as soon as it starts, your next step is to do a block test, go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
TEST 3: Engine Compression Test
Every now and then when a head gasket gets blown, it's going to burn right between two adjacent cylinders.
The photo at the beginning of this tutorial shows this type of head gasket failure.
When this happens you're gonna' have two dead cylinders causing the engine to idle very rough and misfire.
These two dead cylinders are caused by the fact that the head gasket now allows the compression of one cylinder to escape into the other.
These are the test steps:
- 1
Remove all six spark plugs.
Disable the ignition system by disconnecting the distributor from its engine wiring harness connector. - 2
Thread in 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. - 3
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.
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). - 4
Repeat steps 1 through 3 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.
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.
