TEST 2: Removing The Valve Cover To Expose The Timing Belt

Aligning the Timing Marks on the Camshaft and Crankshaft Pulley. How To Check For A Broken Timing Belt (2.0L Mazda 626 and MX6)

This last test involves physically checking that the timing belt isn't broken or loose. You'll also be able to make sure that the timing marks align up.

All this is accomplished by removing the valve cover and exposing both the timing belt and the 2 camshafts. Once the camshafts are exposed, you can now manually turn the engine.

If you're wondering how to ‘manually turn the engine’ (in other words, cranking the engine without using the starter motor), a ratchet wrench and a socket are used on the crankshaft pulley. The crankshaft pulley is then turned till the timing marks align up on the camshaft gears. I'll explain how in the test steps below:

  1. 1

    Disconnect the battery negative (-) terminal from the battery negative (-) post.

  2. 2

    Now, using the appropriate tools, remove the valve cover.

    You can remove the top timing belt plastic cover but you don't have to.

  3. 3

    Once the valve cover is removed and the camshaft gears are exposed, turn the engine using a ratchet wrench (and the appropriate socket) on the crankshaft pulley.

  4. 4

    As the engine is turning, align the timing mark on the crankshaft pulley with the 0 mark on the lower timing belt cover.

    At this point, both camshaft gear dowel pins should be pointing straight up (see the orange arrows with the number 1 in the illustration above) and the letters I and E should be pointing to each other. (I stands for Intake, and E for Exhaust).

    If the camshaft marks don't align, then turn the crankshaft one complete revolution clockwise till the mark on the crankshaft pulley aligns with the mark on the lower timing cover again. Now, check that to see if the marks align on the camshaft gears.

    NOTE: The illustration above shows the camshaft gears without their center bolts. This is done to make it easier to show the dowel pins only. Do not remove or loosen the camshaft gear bolts on your vehicle to perform this test or you will lose the timing belt synchronization. The dowel pins can be seen with the camshaft gear bolts in place.

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

CASE 1: The timing belt is not busted and the timing marks align as indicated. This is a clear indication that the timing belt on your 2.0L Mazda 626 (or 2.0L MX6) is not broken.

CASE 2: The timing belt is busted or the timing marks DID NOT align as indicated: This is bad news and confirms that the timing belt is behind your vehicle's no start condition.

Since the 2.0L Mazda engine is an interference engine, there's a strong likelihood that the valves have hit the pistons and are bent.

More 2.0L Mazda Tutorials

If this tutorial was helpful, check out the other Mazda 2.0L tutorials that I've written. You can find them all here: Mazda 2.0L Index of Articles.

Here's a small sample of the tutorials you'll find in the index:

  1. How To Test For A Blown Head Gasket (2.0L Mazda 626).
  2. How To Test The MAF Sensor (1996-1997 2.0L Mazda 626).
  3. How To Test The TPS (1994-2002 2.0L Mazda 626).
  4. How To Test The MAF Sensor (1996-1997 2.0L Mazda 626).
  5. How To Test The Fuel Pump (1994-1999 2.0L Mazda 626).