How To Test A Blown Head Gasket (1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 4.3L V6 Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma, And Isuzu Hombre)

If you suspect your Chevrolet S10 pickup, GMC S15 pickup or GMC Sonoma's 4.3L V6 engine has suffered a blown head gasket, this tutorial will walk you through the blown head gasket testing process.

All four blown head gasket tests are explained step by step, and you'll quickly determine if a blown head gasket is causing an engine no-start or an engine overheating problem.

In Spanish You can find this tutorial in Spanish here: Cómo Probar Los Empaques De Cabeza (1988-2003 4.3L V6 Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

  • 4.3L V6 Chevrolet S10 Pickup: 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003.
  • 4.3L V6 GMC S15 Pickup: 1988, 1989, 1990.
  • 4.3L V6 GMC Sonoma: 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003.
  • 4.3L V6 Isuzu Hombre: 1997, 1998, 1999, 2000.

Symptoms Of A Blown Head Gasket

A blown head gasket issue will usually cause one of two problems:

  • An engine no-start.
  • The engine starts but overheats immediately and for no apparent reason.

Here's a basic list of the symptoms you'll see when your 4.3L V6 Chevrolet S10 pickup, GMC S15 pickup or GMC Sonoma suffers a head gasket failure:

  • The engine overheats for no apparent reason. All engine cooling system components (like fan clutch/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 (1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 4.3L V6 Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma, And Isuzu Hombre)

For our first test, we'll check the color and viscosity of the oil sticking to the engine's oil level dipstick.

If your Chevrolet S10 pickup, GMC S15 pickup or GMC Sonoma's 4.3L V6 engine has suffered a blown head gasket, its engine oil may be mixed with engine coolant.

When the engine oil and engine coolant mix, the engine oil will look like coffee with too much creamer.

These are the test steps:

  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.

OK, let's find out what your test result means:

CASE 1: The engine oil has the color of coffee with too much creamer. This test result confirms that one or both head gaskets are blown on your 4.3L V6 Chevy S10 pickup (GMC S15 pickup, GMC Sonoma).

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.

Chevrolet Vehicles:

  • S10 Pickup 4.3L
    • 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003

GMC Vehicles:

  • S15 Pickup 4.3L
    • 1988, 1989, 1990
  • Sonoma 4.3L
    • 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003

Isuzu Vehicles:

  • Hombre 4.3L
    • 1997, 1998, 1999, 2000