Checking whether your 4.0L Ford Explorer (4.0L Ranger, 4.0L Aerostar, or 4.0L Mountaineer) has a blown head gasket can be done with one of three different tests and in this article I'll show you how to do them and how to interpret the results you'll obtain from them.
To get you where you need to be, in this article, here are its contents at a quick glance:
To successfully accomplish the tests in this article, I suggest you follow these tips:
TIP 1: Read the entire article first. The first two tests can be done in under 10 minutes, if you know what you're looking and testing for.
TIP 2: You'll need an engine compression tester for HEAD GASKET TEST 3.
TIP 3: You'll be working around a cranking engine as you perform HEAD GASKET TEST 2 and HEAD GASKET TEST 3, so be careful and take all necessary safety precautions.
A blown head gasket is the result of the engine overheating and usually, one of the tell tale signs is coolant mixing with the engine oil. This first test will confirm whether this has happened or not. This is the test:
Open the hood and pull out the engine's oil dipstick.
Now, look at the engine oil that's sticking to the dipstick. It will be one of two colors:
1.) Either the engine oil will be a creamy tan/off white color and as thick as syrup Or...
2.) The engine oil is a normal color and viscosity.
This is what the color of the engine oil means:
CASE 1: The color of the oil is a tan/off white color., this is bad news and indicates that your 4.0L Explorer (or Ranger, Aerostar, Mountaineer) overheating to the point the one (or both) of the head gaskets burned.
CASE 2: The color of the engine oil is normal, So far so good, but this result doesn't really confirm that the head gaskets are OK. You'll need to do the other two tests to further confirm a BAD head gasket or exonerate the head gasket. Go to HEAD GASKET TEST 2.
Here's why: Most of the time when the vehicle overheats and one of the head gaskets burns... it will let coolant into the crankcase... but not always. Thankfully, there are several more tests that can be done to confirm that the head gasket is blown or exonerate it as the cause of the issue. If in your case this test was inconclusive, the next test is to see if the engine's compression/ combustion gases are escaping thru' the radiator.
“For instance, on the planet Earth, man had always assumed that he was more
intelligent than dolphins because he had achieved so much —the wheel,
New York, wars and so on —whilst all the dolphins had ever done was
muck about in the water having a good time. But conversely,
the dolphins had always believed that they were far more
intelligent than man —for precisely the same reasons!”
The Hitchhiker's Guide to the Galaxy