How To Test A Blown Head Gasket (GM 3.8L)

If you suspect that your 3.8L GM vehicle (whether it's a Buick, a Chevy, a Pontiac, or an Olds) has a blown head gasket and don't know how to test this... well, you've found the right article. I'm gonna' show you how to do four of the most common tests to verify a blown head gasket.

All four tests are explained in a step-by-step fashion and more importantly, I'll explain the test results that you'll obtain from the tests.

En Español You can find this tutorial in Spanish here: Cómo Probar los Empaques de las Cabezas (3.8L V6 GM) (at:

Symptoms Of A Blown Head Gasket

The most common cause of a blown head gasket is that the engine overheated because: 1) fan clutch is not working, 2) All of the coolant leaked out of the engine and you kept driving it this way. 3) Thermostat went BAD and is stuck closed and the coolant could not circulate. The most common symptoms a blown head gasket are:

  1. Your 3.8L GM car or mini-van is overheating. You have confirmed that the overheating issue is not being caused by an inoperative fan or a bad thermostat.
  2. White smoke is coming out of the tail-pipe and it smells like anti-freeze being cooked.
  3. Your 3.8L GM car or mini-van won't start. You have already verified it's not an ignition system problem because you have spark coming out at all of the spark plug wires. You know it's not a lack of fuel, because you have verified that the fuel pump is delivering fuel to the fuel injectors.
  4. The engine oil is thick and tan to off-white color (mixed with coolant).

TEST 1: Checking The Color Of The Engine Oil

How To Test A Blown Head Gasket By Checking The Color Of The Engine Oil (GM 3.8L)

The first two tests are the fastest and the easiest to do and they are very accurate too. The first test or the second may be enough to verify that the head gasket is blown on your GM 3.8L equipped car or mini-van, so there's a good possibility that you may not have to do all four. So, before you start on this first test, take a look at the whole article.

Alright, this test should take you less than 2 minutes to do:

  1. 1

    Pop the hood on your 3.8L GM car or mini-van and once open, check the engine oil by pulling out the engine's oil dipstick.

  2. 2

    The idea behind this test is to see if coolant is mixing with the engine oil and so you'll notice one of two things:

    1.) Either the color of the engine oil will be an off-white/tan color or...

    2.) The oil is its normal color and viscosity.

Now, let's find out what each of the two results mean:

CASE 1: The engine oil is an off-white/tan color, and your car or mini-van overheats and/or doesn't start, this confirms that your vehicle has a blown head gasket.

Why does the oil look like this? Mainly because your 3.8L GM car or mini-van over-heated and :

1.) The cylinder head (or heads) warped and one of the two head gaskets on your 3.8L engine burned.

2.) Once one of the two head gaskets on your engine burns, it won't be able to keep the engine oil or coolant separated...

3.) ...this will lead to the coolant entering the engine oil pan.. As both oil and coolant mix... the resulting combination gets thick and becomes an off-white color.

CASE 2: The color of the engine oil is normal. So far so good since this is the correct and expected test result. But if your vehicle is still overheating (and you've verified that the thermostat and cooling fans are OK)... you'll need to continue onto the next test or tests. Go to TEST 2: Compression Gases Escaping from an Open Radiator.

Here's why: In most cases, when one of the head gaskets burns on a 3.8L GM car or mini-van, the coolant does mix with the engine oil. But not always, and so then, there's the need to do some more tests. The next test is to see if the engine compression and exhaust gases are escaping thru' the cooling system (specifically the radiator).