A broken timing belt will cause the engine to 'crank but not start', but so will a host of other things. So, if you're wondering how to test it, in this tutorial I'll explain how.
I think you'll be surprised just how easy it is to find out if the t-belt is good or if it's busted (and causing the engine not to start).
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar Si La Correa De Distribución Está Rota (1995-2000 2.0L Dodge Stratus, Plymouth Neon) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 2.0L Dodge Stratus: 1995, 1996, 1997, 1998, 1999, 2000.
- 2.0L Plymouth Breeze: 1996, 1997, 1998, 1999, 2000.
Symptoms Of A Broken Timing Belt
The timing belt is crucial for starting and keeping the engine running. Its job is to ensure the engine's crankshaft and camshaft rotate in sync. This synchronization is vital because it controls when the engine's valves open and close during the intake and exhaust strokes of each cylinder.
In the 2.0L Dodge Stratus (and Plymouth Breeze), which has an interference engine, the timing belt’s role is even more critical. It prevents the pistons and valves from colliding inside the engine. If the t-belt breaks, the pistons will strike the valves, causing extensive damage such as bent valves, broken pistons, and cylinder head or camshaft damage.
Therefore, if the timing belt breaks, the engine won't start. If it breaks while the engine is running, the engine will stall and won't restart.
In case you're wondering what an "interference engine" is, it's a type of internal combustion engine design in which the space paths of the piston and the valves overlap.
In other words, the design of the engine is such that if the timing belt breaks, the pistons and valves collide, because they occupy the same space in the cylinder at different times. This design contrasts with a "non-interference engine," where there is no risk of piston and valve collision if the timing belt or chain fails.
TEST 1: Checking The Timing Marks On the Camshaft Gear Timing And Rear Timing Belt Cover
To check the condition of the t-belt, we're gonna set the number 1 piston to its top-dead-center position on its intake stroke. If you've never done this before, don't worry. In the test steps below, I've explained the whole process in detail.
Once the number 1 piston is set to its top-dead-center position, we'll check that the timing marks on the camshaft gear and the back timing belt cover line up.
If the timing marks on both components line up (see the illustrations in the image viewer above), you've now know that the timing belt is OK and is not the cause of the engine no-start problem you're trying to diagnose.
IMPORTANT: Make sure your Stratus (Breeze) 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:
Disconnect the negative battery cable from the battery.
Raise and place the front of your vehicle 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.
Remove the front passenger-side tire.
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.
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.
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.
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).
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).
Rotate the crankshaft one full revolution and stop when the screwdriver has reached its maximum upward travel.
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.
If the engine is not starting on your Dodge Stratus (or Plymouth Breeze), you can rule out the t-belt as the cause of the issue.
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 Dodge Stratus (or Plymouth Breeze) 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.
If this info saved the day, buy me a beer!