Tools and Materials Needed:
- Replacement timing belt (OEM or recommended brand)
- Timing belt tensioner
- Socket wrench set
- Torque wrench
- Flat-blade screwdriver
- Long-nose pliers
- Chalk or marker
Steps:
1. Preparation:
- Park your car on a level surface and engage the parking brake.
- Disconnect the negative terminal of your car's battery to avoid accidental electrical contact.
2. Remove the Serpentine Belt:
- Locate the serpentine belt (it runs various accessories such as the alternator, power steering pump, and air conditioning compressor).
- Loosen the tensioner bolt using the appropriate size wrench, then remove the serpentine belt.
3. Access the Timing Belt:
- Remove the timing belt cover by unscrewing the bolts holding it in place. This will expose the timing belt and its components.
4. Set the Engine to TDC (Top Dead Center):
- Using a socket wrench, align the crankshaft pulley mark with the 0-degree mark on the engine's timing cover.
- Next, align the camshaft marks (intake and exhaust) to match the corresponding marks on the cylinder head. To do this, gently rotate the crankshaft while watching the camshaft gears until the marks align.
5. Install the Timing Belt Tensioner:
- Remove the old tensioner by unscrewing its mounting bolts.
- Install the new tensioner in place, ensuring that the arrow on the tensioner matches the direction indicated in the service manual for your specific Miata model.
6. Install the Timing Belt:
- With the engine still at TDC, start installing the new timing belt.
- Start by routing the belt around the crankshaft gear and then the water pump.
- Next, wrap the belt around the idler pulley and tensioner pulley.
- Finally, loop the belt around the camshaft gears, making sure that the appropriate alignment marks are aligned.
7. Adjust Timing Belt Tension:
- Once the timing belt is installed, adjust its tension using the tensioner tool.
- Follow the proper procedure as specified in your Miata's service manual to ensure the correct belt tension.
8. Reinstall the Timing Belt Cover:
- Reattach the timing belt cover by inserting the cover bolts and tightening them securely.
9. Reinstall the Serpentine Belt:
- Put the serpentine belt back in place, ensuring proper alignment with its respective pulleys.
- Tighten the tensioner bolt to secure the serpentine belt.
10. Double-Check Alignment Marks:
- Ensure that all timing marks (crankshaft pulley, camshaft gears, and tensioner) are still aligned correctly.
11. Reconnect the Battery:
- Reconnect the negative terminal of the car battery.
12. Test the Engine:
- Start the engine and observe if it runs smoothly without any unusual noises or vibrations due to misalignment.
13. Road Test:
- Take your Miata for a short test drive to ensure that the timing belt replacement has been successful.
14. Final Inspection:
- After the road test, inspect the timing belt area for any leaks, loose bolts, or signs of misalignment.
Note: While this guide provides general steps for replacing the timing belt on a 1990 Mazda Miata, it is essential to consult your car's specific service manual for model-specific instructions and torque specifications. If you are not confident in your mechanical skills, it's best to seek assistance from a qualified mechanic or refer to a professional repair manual.
