TEST 2: Exhaust Shooting Out Of The Radiator
This next blown head gasket test will check to see if the exhaust gases (that the engine produces as it cranks) are escaping thru' the cooling system of your Ford vehicle.
By the cooling system, I mean the radiator.
OK, here are the test steps:
Remove the radiator cap from the radiator.
Check to see if the radiator is full. If not, top it off with water.
Have your helper crank the engine as you stand at a safe distance observing the open radiator.
You'll see one of two results:
1.) The water or coolant will shoot up and out of the now open radiator like a geyser.
2.) The coolant was not be disturbed. To be more specific: cranking the engine does not cause the coolant to shoot out of the open radiator.
OK, now that the testing part is done, let's take a look at what your results mean:
CASE 1: The coolant bubbled out or shot out from the radiator. This is bad news and tells you that YES do have a blown head gasket problem on your hands. You do not need to perform TEST 3.
CASE 2: The coolant DID NOT bubble out NOR shoot out from the radiator. It's starting to look like you do not have a blown head gasket problem. To make absolutely sure the head gasket is OK, go to: TEST 3: Engine Compression Test
Now, common sense tells you that if a head gasket is blown, you ARE gonna' have oil mixed with coolant, and engine compression and/or combustion gases are going to be shooting out of the radiator but sometimes this just doesn't happen. So, the next test will further confirm or exonerate the head gasket.
TEST 3: Engine Compression Test
One of the most overlooked tests, to see if the head gasket is bad or not, is an engine compression test. Why? Well because most folks will do the two previous tests (TEST 1 and TEST 2) and they will not see the engine oil mixing with the coolant nor see the combustion gases jumping out of the open radiator and conclude everything is OK. And whatever information they have available never mentions testing the engine compression.
Well, now you know that it is possible for the head gasket to burn and not cause the oil to mix with coolant nor cause the exhaust gases to escape thru' the cooling system. In this test step, you'll be doing a compression test and more importantly, you'll be able to easily interpret those results (with my help) to further confirm or exonerate a blown head gasket.
This test will see if the head gasket on your 4.9L, 5.0L, 5.8L Ford van (car, pick up, SUV) has burned at a point between cylinders.
If this does happen, the compression/combustion of one cylinder to leak into the other and vice-versa and the compression readings will easily let us know this has happened.
OK, here's what you need to do:
Disable the ignition system on your 4.9L, 5.0L, 5.8L Ford van (car, pick up, SUV). It's important that spark is not created and delivered to the spark plug wires.
You can easily accomplish this ‘disabling’ by disconnecting the ignition module's electrical connector or the ignition coil's electrical connector.
Disable the fuel system. It's important that fuel not be injected into the engine.
You can do this by disconnecting the fuel pump relay.
Disconnect all spark plug wires (from their spark plugs).
NOTE: It's a very good idea to label all of the spark plug wires before disconnecting them from their spark plugs. This will avoid losing the spark plug wires' firing order.
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. Your job is to observe the compression tester.
Once the compression tester's needle stops climbing, have your assistant stop cranking the engine.
Now, write down the reading and what cylinder it belongs to (you can use the illustration above to help you identify the cylinder) on a piece of paper.
Remove the compression tester and repeat the above steps in the remaining cylinders.
OK, before I jump into the above compression test result interpretations, let me give you some more detailed information as to what you're trying to accomplish with this test, If the head gasket is burned at a location between 2 cylinders, your compression test readings will give you 2 side-by-side compression readings that will be 0 PSI on the same bank of cylinders. Let me give you a more specific example:
Let's say that I tested my 5.0L Ford F150 and I got the following compression tester readings:
- Cylinder #1 = 165 PSI
- Cylinder #2 = 0 PSI
- Cylinder #3 = 0 PSI
- Cylinder #4 = 170 PSI
- Cylinder #5 = 180 PSI
- Cylinder #6 = 170 PSI
- Cylinder #7 = 175 PSI
- Cylinder #8 = 185 PSI
The compression readings for cylinders #2 and #3 would be a dead giveaway that the head gasket got fried between those two cylinders. Now, in your specific Ford van (car, pick up, SUV), you may not see those exact same cylinders with 0 PSI readings. It may be #1 and #2 or it may be #5 and #6, the key here, is that whatever cylinders are affected, two of them will have 0 PSI compression and they will be both be side by side and on the same bank.
CASE 1: All cylinder compression readings where normal. These compression gauge readings confirm that the head gasket is OK and not burned at a point between two cylinders.
So far, 3 out of 4 tests have confirmed that the head gasket on your 4.9L, 5.0L, 5.8L Ford van (car, pick up, SUV) is not blown. But, and there's always one, if your Ford is still overheating for no apparent reason, go on to the next test: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)
CASE 2: Two side by side cylinders had 0 PSI Compression: This engine compression reading confirms that the head gasket is burned thru' at the point between those two cylinders. You will need to replace the head gasket.