How To Test For A Broken Timing Belt (1995-2005 2.0L SOHC Dodge/Plymouth Neon)

The timing belt in your Dodge/Plymouth Neon plays a crucial role in starting and keeping the engine running.

If the timing belt isn't changed according to the manufacturer's specified interval, it'll break, causing your Neon's engine not to start.

If you're wondering if the timing belt broke (and is behind the engine's no-start problem), this tutorial will guide you through how to check it. The good news is, you won't need any fancy tools to perform this test.

NOTE: This tutorial only applies to the 2.0L SOHC engine (Single Overhead Camshaft). The 2.0L SOHC engine in the Dodge/Plymouth Neon is an interference engine.

You can find this tutorial in Spanish here: Cómo Probar Si La Correa De Distribución Está Rota (1995-2005 2.0L SOHC Dodge/Plymouth Neon) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 2.0L Dodge Neon: 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.
• 2.0L Plymouth Neon: 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.

Symptoms Of A Broken Timing Belt

The most common and obvious symptom of a broken timing belt is that your Neon's engine will 'crank but not start'.

The other thing you'll notice is that the engine cranks faster than normal when you turn the key to start it.

Here's why: When the timing belt breaks, the synchronization between the crankshaft and camshaft is lost. This means the valves won't open and close at the right times, disrupting the engine's ability to draw in air and fuel, compress them, and ignite the mixture. Due to this lack of compression, the engine will usually crank faster than normal and not start.

TEST 1: Checking The Timing Marks On the Camshaft Gear Timing And Rear Timing Belt Cover

The timing belt cover on your 2.0L SOHC Neon has an access plug that you can remove (see photo 1 of 2 above) and check the alignment of the timing marks on the camshaft gear and the rear timing belt cover (when the #1 piston is at top dead center on its intake stroke).

If after setting the #1 piston to its top dead center (TDC) position (on its intake stroke) and both timing marks don't line up, then you can conclude that the timing belt is busted.

In the test steps below, I'll walk you step-by-step thru the process of setting the #1 piston to its top dead center position.

IMPORTANT: Make sure your Neon is in "Park" or "Neutral" and that the emergency brake is engaged. Keep your hands, clothing, and any tools well clear of any moving parts in the engine bay.

These are the test steps:

1. 1

   Disconnect the negative battery cable from the battery.

2. 2

   Raise and place the front of your Neon on jack stands.
   
   Lifting up the front end (and placing it on jack stands) will allow you easy access to the the crankshaft pulley bolt in the step 6.

3. 3

   Remove the front passenger-side tire.

4. 4

   Remove all four spark plugs.
   
   NOTE: You don't need to remove all four spark, you can just remove the #1 cylinder spark plug. I recommend removing all of them to make it easier to manually turn the engine in step 5.

5. 5

   Insert a long screwdriver into the #1 cylinder spark plug hole.
   
   NOTE: Cylinder #1 is the cylinder closest (right next to) the serpentine drive belt.
   
   In case you're wondering, the long screwdriver will sit right on top of the piston. When the piston moves, it'll push the screwdriver either up or down. The movement of the screwdriver will be your visual indicator of the piston's position.
   
   IMPORTANT: Have a helper hold the long screwdriver so that it doesn't bind or get stuck in the spark plug hole as the piston pushes it up in the next step.

6. 6

   Slowly turn the crankshaft clockwise with a ratchet wrench and the appropriate size socket.
   
   Depending on the position of the piston, the long screwdriver will either move down or move up. What you're wanting to happen is for the screwdriver to start being pushed up by the piston.

7. 7

   Stop rotating the crankshaft when the screwdriver gets to a point where it has reached it's maximum upward movement and it's about to start moving down.
   
   NOTE: The point where the piston has reached is maximum upward travel and it's about to move down is called the 'top dead center' point (of its intake or exhaust stroke).

8. 8

   Check the camshaft gear timing mark alignment thru the access hole on the timing belt cover. It should align with the arrow on the back timing belt cover (see photo 3 of 3 in the image viewer above).
   
   If both timing marks do not line up, go to step 9.
   
   If the timing marks line up, skip step 9 and go to the test interpretations (CASE 1, CASE 2).

9. 9

   Rotate the crankshaft one full revolution and stop when the screwdriver has reached its maximum upward travel.

10. 10

    Check the camshaft gear timing mark alignment thru the access hole on the timing belt cover. It should align with the arrow on the back timing belt cover.
    
    If they do or don't line up, go to the test interpretations below.

Let's interpret your test result:

CASE 1: The timing marks on the camshaft gear and rear timing belt cover line up with the #1 cylinder piston at TDC. This tells you that the timing belt is OK.

CASE 2: The timing marks on the camshaft gear and rear timing belt cover DO NOT line up with the #1 cylinder piston at TDC. This test result tells you that the timing belt is broken.

The 2.0L SOHC engine in your Neon is an interference engine. If the timing belt is broken, more than likely some of the cylinder head valves are bent. This happens because when the t-belt breaks, the pistons and valves come into contact with each other, which leads to damage to the valves or pistons or both.

Intake And Exhaust Stroke Top Dead Center Basics

You've probably noticed that I've mentioned that there's a top dead center (TDC) on the intake and exhaust stroke of the piston. In this section I'll explain this in detail, since the camshaft gear timing mark will only align with the timing mark on the rear timing belt cover on the intake stroke TDC piston position.

In an engine, there are four strokes that a piston goes through as it moves up and down inside a cylinder. These strokes are called the "intake," "compression," "power," and "exhaust" strokes. When we talk about the "intake or exhaust stroke," we're referring to two of these strokes. Here's what they mean:

• Intake Stroke: During the intake stroke, the piston moves downward in the cylinder. This creates a vacuum, and the intake valve opens to allow air (and fuel in a gasoline engine) to be drawn into the cylinder. This stroke starts with the piston at the top of the cylinder and ends with it at the bottom.
• Exhaust Stroke: The exhaust stroke follows the power stroke. In this stroke, the piston moves upward in the cylinder, and the exhaust valve opens. This allows the burned gases from the previous power stroke to be expelled from the cylinder. The exhaust stroke also starts with the piston at the top and ends with it at the bottom.

In the 1995-2000 2.0L SOHC engine, the timing marks are aligned at the intake stroke TDC because the intake stroke TDC is the reference point for valve timing, and it's the moment when the #1 piston is at the top of its travel and the intake valve is just about to open to let in air and fuel.

The test steps take all of this into consideration. If, during your first attempt (of setting the piston to top dead center), you didn't see the timing marks on the camshaft gear and rear timing belt cover line up, there's a good chance you were at the exhaust stroke TDC. In this case, the instructions ask you to rotate the crankshaft one full revolution and set the piston to top dead center once more. Then, recheck the alignment of the timing marks thru the timing belt cover's access hole.