How to Verify Timing Belt Is Broken (Interference)

VERIFYING TIMING BELT IS BROKEN
Check for camshaft rotation while cranking the engine (with the starter or by hand, using the crankshaft bolt).

WARNING: When rotating the crankshaft by hand always disconnect the battery.

Camshaft rotation may be verified by:
- Remove oil filler cap and check if camshaft is visible.
- Remove valve cover and directly observe camshaft.
- Remove distributor cap and check for rotor rotation (the rotor is driven by the camshaft)
- Remove upper timing belt cover and check camshaft pulley rotation and belt integrity.

Other Indications The Timing Belt May Be Broken
- No ignition spark.
- Very low compression (<15 psi) on all cylinders. Due to the low compression the following additional symptoms may be present.
- While attempting to start the car, the battery strength remains high for an unusually long length of time.
- The sound of the engine while attempting to restart will be different than normal. Instead of the usual rhythmic "Rir. . .Rir. . .Rir. . ." cranking sound it will sound more like "RirRirRirRir" with no detectable rhythm.

NOTE: For an experienced technician this unique sound will often be the initial symptom that leads to a more in-depth check of the timing belt.

Check for Valve Damage
- Remove the valve covers and inspect valve clearances. A valve which is bent should be stuck in the partially open position (verify the hydraulic lifter is not collapsed).

WARNING: Rotating the camshaft with the timing belt removed or broken on an interference engine can result in additional valve damage.

- If any valve damage is detected the cylinder head will need to be removed.

- If no valve damage is detected continue with replacing the timing belt.

NOTE: Valve damage may still exist, after aligning and installing the timing belt, check engine compression to verify the condition of the valves. Compression will be low on any cylinder with bent valves.