How To Diagnose A No-Start Problem (1995-1999 3.1L V6 Chevrolet Lumina, Monte Carlo)

STEP 3: Checking For A Blown Head Gasket

A blown head gasket (and your Lumina or Monte Carlo's 3.1L V6 engine has two of them) can cause the engine to not start.

In the majority of cases, a blown head gasket is usually caused by severe engine overheating.

There are four specific tests to check for a head gasket, in this section I'm gonna' explain how to do 2 of those 4.

If you want to find out more about all 4 tests, check out this tutorial:

• How To Test For A Blown Head Gasket (GM 3.1L, 3.4L) (at troubleshootmyvehicle.com).

These are the test steps:

1. 1

   Open the hood.

2. 2

   Remove the dipstick.

3. 3

   Check the color of the oil sticking to the dipstick.

4. 4

   You'll see one of two things:
   
   1.) The oil will look like 'coffee with too much creamer'.
   
   2.) The oil will look normal.

5. 5

   Remove the radiator cap from the radiator.
   
   CAUTION: Never remove the radiator cap if the engine is hot or has been running an extended amount of time. Wait till the engine has completely cooled down before removing the radiator cap.

6. 6

   Check the coolant level. If the radiator is not full, then top it off with water.

7. 7

   Have your helper to crank the engine, while you stand at a safe distance from the open radiator.

8. 8

   You'll see one of two results:
   
   1.) The water or coolant inside the radiator will shoot out.
   
   2.) The coolant will not be disturbed. In other words, cranking the engine will have no effect on the level of the water or coolant in the radiator.

Let's take a look at what your test results mean:

CASE 1: The oil on the dipstick looks like 'coffee with too much creamer'. This test result lets you know that you've have a blown head gasket problem on your hands.

CASE 2: The coolant was shot out of the open radiator when the engine was cranked. This test result lets you know that you've have a blown head gasket problem on your hands.

CASE 3: The coolant WAS NOT shot out of the open radiator when the engine was cranked and the oil looks its normal color on the dipstick. These are the correct test results.

Since your Chevrolet Lumina or Monte Carlo's engine is not starting, your next test is to check the engine's compression. Go to: STEP 4: Making Sure The Engine Has Good Compression.

STEP 4: Making Sure The Engine Has Good Compression

If you have eliminated the ignition system, the fuel pump, and a blown head gasket as the cause of your Chevy Lumina or Monte Carlo's no-start problem, then the next step is to test the engine's compression.

I've written a detailed ‘how to test the engine compression’ tutorial, and you can find it here:

• How To Test The Engine Compression (1995-1999 3.1L V6 Chevrolet Lumina, Monte Carlo).

This is what you'll need to do:

1. 1

   Disconnect the spark plugs wires from the spark plugs.

2. 2

   Remove the spark plugs.

3. 3

   Thread the engine compression gauge into the spark plug hole for the number 1 engine cylinder.
   
   Hand tighten the compression gauge only! Do not use any type of tool to get it tight.

4. 4

   Have your helper crank the engine.

5. 5

   Once the needle on the compression gauge stops climbing have your helper stop cranking the engine.

6. 6

   Now, record the value on a piece of paper and the cylinder it belongs to.

7. 7

   Repeat steps 3 and 6 on the remaining cylinders.

Let's take a look at what your compression test results mean:

CASE 1: All cylinders have compression above 120 PSI. This is the correct and expected test result.

If all cylinders have at least 120 PSI of compression, then you can conclude that the engine does not have a compression problem (causing it not to start).

CASE 2: All cylinders have 0 PSI compression. This tells you that 0 compression is the cause behind the no-start problem on your Chevrolet Lumina (Monte Carlo).

The most likely cause will be a broken timing chain or the engine threw a rod.

CASE 3: Two adjacent cylinders have 0 PSI. This usually indicates a blown head gasket. Specially if your Chevy Lumina or Monte Carlo's engine overheated before the no-start problem occurred.

For more testing suggestions, take a look at this tutorial: How To Test A Blown Head Gasket (3.1L V6 Chevrolet And Pontiac Vehicles).

No Start Troubleshooting Summary

The most important thing to remember when diagnosing an engine no-start problem, is that the engine needs 3 things to be able to start.

These 3 things are:

• Spark.
• Fuel.
• Air (compression).

When the engine does not start, it's because one of these is missing from the mix.

Therefore, testing an engine no-start problem literally boils down to a process of elimination.

By checking these basic things (spark, fuel, air), you'll save yourself the frustration of replacing components that won't solve the problem.

As you noticed, I started out the troubleshooting tests with a spark test (at all cylinders). This is due to the fact that the culprit behind most no-start problems is the ignition system, specifically a defective 7X crankshaft position sensor.

Once you've confirmed that you've got spark at all cylinders, there isn't any need to spend time testing the 7X crankshaft position sensor. The next step is to make sure the fuel pump is working and so on and so on.

Where To Buy An HEI Spark Tester And A Fuel Pressure Gauge

As I mentioned before, the HEI spark tester (OTC 6589) is an accurate spark tester and it doesn't cost and arm and a leg. The fuel pressure gauge that connects to the Schrader Valve on the fuel rail (of your Chevrolet Lumina or Monte Carlo) is a reasonably priced tool too: