Blown Head Gasket Tests (2002-2004 4.2L Oldsmobile Bravada, 2004-2007 4.2L Buick Rainier)

How To Test A Blown Head Gasket (2002, 2003, 2004, 2005, 2006, 2007 4.2L Oldsmobile Bravada And Buick Rainier)

A blown head gasket can be diagnosed by performing one of four tests and in this tutorial, I'll explain how to perform them step-by-step.

You'll quickly and easily find out if a blown head gasket is causing an engine no-start or an overheating problem.

APPLIES TO: This tutorial applies to the following vehicles:

  • 4.2L L6 Buick Rainier: 2004, 2005, 2006, 2007.
  • 4.2L L6 Oldsmobile Bravada: 2002, 2003, 2004.

Symptoms Of A Blown Head Gasket

For the most part, cylinder head gasket failures fall into one of two categories:

  • The head gasket failure causes the engine not to start.
  • The head gasket failure allows the engine to start and run, but the engine overheats within minutes.

Here's a basic list of the symptoms you'll see when your 4.2L Oldsmobile Bravada (Buick Rainier) suffers a head gasket failure:

  • The engine overheats for no apparent reason. All engine cooling system components (like fan motor, water pump, etc.) are working fine.
  • White smoke is coming out of the tail-pipe and it smells like anti-freeze being cooked.
  • The engine won't start.
  • The engine oil is thick and a milky white color.

TEST 1: Engine Oil The Color Of ‘Coffee With Too Much Creamer'

Engine Oil The Color Of Coffee With Too Much Creamer. How To Test A Blown Head Gasket (2002, 2003, 2004, 2005, 2006, 2007 4.2L Oldsmobile Bravada And Buick Rainier)

The most common result produced by a blown head gasket is coolant entering the crankcase.

As the engine oil to mixes with the coolant, it'll turn into a gooey mess that resembles coffee with too much creamer.

So the first thing that we'll do, is check the condition of the engine oil adhering to the engine oil level dipstick.

  1. 1

    Open the hood.

  2. 2

    Pull out the engine oil dipstick.

  3. 3

    Check the color of the oil (sticking to the engine oil dipstick).

  4. 4

    You'll see one of two results:

    1.) The engine oil looks like coffee with too much creamer.

    2.) The engine oil is its usual normal color.

Alright, let's analyze your test result:

CASE 1: The engine oil has the color of coffee with too much creamer. This test result confirms the head gasket is blown on your 4.2L Oldsmobile Bravada (Buick Rainier).

CASE 2: The color of the engine oil is normal. This is the correct and expected test result.

The next test is to see if the engine's compression pressures are escaping into the engine's cooling system (radiator). For this test go to: TEST 2: Coolant Shooting Out From Open Radiator.

Buick Vehicles:

  • Rainier 4.2L
    • 2004, 2005, 2006, 2007

Oldsmobile Vehicles:

  • Bravada 4.2L
    • 2002, 2003, 2004