Variable Valve Timing Noise Complaints When Starting Mazda MZR Engine - Engine Builder Magazine

Variable Valve Timing Noise Complaints When Starting Mazda MZR Engine

Affected Models with MZR engine

2007 Mazdaspeed3 vehicles produced before April 1, 2007

2006-2007 Mazdaspeed6 vehicles produced before April 1, 2007

2007 Mazda CX-7 vehicles produced before April 1, 2007


When the engine is first started, some vehicles may exhibit a loud ticking noise from the variable valve timing (VVT). This is caused by the lock pin of the variable valve timing actuator not fully engaging.

Heat treatment has now been added around the hole of the variable valve timing rotor lock pin to prevent this from happening.

Customers having this concern should have their vehicle repaired using the following repair procedure.  


1. Verify variable valve timing noise.

2. After the engine cools down, replace the variable valve timing actuator.

NOTE: Do not use the printed service manual as the procedure has been updated online.

3. Change the engine oil (5W-30) only, then start and let the engine idle for 5 minutes. This is to remove contaminants from the engine.

4. Make sure there is no fuel leakage around the high pressure fuel pump.

5. After the engine cools down, change the engine oil (5W-30) again, and the filter.

6. Verify repair.  

NOTE: This repair calls for the oil to be changed two times.

Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit

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