Timing belt replacement (1.6L and 1.8L)

Before You Start / Safety

This is a high-consequence job: incorrect cam/crank timing can cause no-start or severe drivability problems.
Work on a cold engine and disconnect battery negative terminal.
Support the car securely if raised.
Rotate engine by hand after belt installation before attempting first start.

High-risk quote: “a simple error in positioning the belt could severely compromise engine operation.” (ScegliAuto, retrieved 2026-02-26) https://www.scegliauto.com/en/video/mazda/tutorial/4186/

Required Tools

Socket set including 21 mm for crank bolt
Breaker bar and/or crank holding tool
Torque wrench
Jack + stands
Cooling system drain pan
Allen keys/hex bits as needed for covers/accessories
Marker pen / paint pen for reference marks

Required Parts / Fluids

Timing belt (NB-compatible)
Recommended while open: tensioner/idler(s), water pump, front cam/crank seals if leaking
Coolant for refill/bleed if water pump is replaced
Accessory belts if worn

Model-specific notes (NB1 vs NB2)

NB1 (1998–2000) and NB2 (2001–2005, VVT on many 1.8 models) share broad timing-belt service principles but have year/market-specific details.
Use VIN/year-specific workshop data for exact mark orientation, bolt torques, and part numbers.

Manual-reference quote: BOFI’s workshop-manual index lists separate NB engine manuals (“99-00 for the bp4w 1.8” and “01-05 for the vvt engine”). Retrieved 2026-02-26. https://bofiracing.com/blog/mx5-miata-workshop-manuals/

Step-by-Step Procedure

1) Set engine to reference timing position

Remove covers/accessory components as required to expose timing belt path.
Align crank/cam timing marks per your exact NB manual before belt removal.

2) Remove crank pulley bolt safely

This is often the hardest fastener in DIY jobs.
Use a proper crank-holding strategy and avoid unstable improvised setups.

Community quote: “Put the socket and long breaker bar on crank nut… bump the key… until it breaks loose.” (Miata.net thread; shared method, retrieved 2026-02-26) https://forum.miata.net/vb/showthread.php?t=721482

Note: the forum “starter bump” method is widely discussed but risk-sensitive. Prefer workshop-manual-approved holding methods where possible.

Remove belt tension and take off timing belt.
Inspect idlers/tensioner, water pump, and front seals.
Replace suspect components now (labor overlap is substantial).

4) Install new belt with marks confirmed

Recheck all marks before tensioning.
Set tension according to your exact manual procedure.
Rotate engine by hand through multiple revolutions and confirm marks return correctly.

5) Reassemble and refill/bleed coolant (if pump replaced)

Refit covers, accessories, crank pulley, and belts.
Refill coolant and bleed air if cooling system was opened.

6) First-start verification

Start engine and verify immediate stable idle.
If no-start occurs after timing-belt work, re-check crank trigger/plate orientation and timing alignment before extended cranking.

Community quote: “the number 1 reason for a no start after a timing belt change is that the crank trigger wheel was installed incorrectly.” (Miata.net NB thread, retrieved 2026-02-26) https://forum.miata.net/vb/showthread.php?t=794130

Community confirmation quote: “It was the trigger wheel after all… I had indeed installed it backwards… flipping it around made all the difference. Put it back the correct way… and it started right up!” (same thread) https://forum.miata.net/vb/showthread.php?t=794130

Torque Specs / Capacities

Because of model-year/market variation and mixed public-source quality, treat these as cross-check references only and prioritize factory manual values for your VIN.

Public NA/NB compilation references exist for many fasteners (including timing-system area), but they are explicitly user-compiled and not a factory publication.

High-risk quote: “I am not responsible for any that are incorrect…” (Apex Drag NA/NB compiled table disclaimer, retrieved 2026-02-26) https://theapexdrag.com/mx-5-na-nb-torque-assembly-specs/

Verification / Post-service checks

No abnormal noises at idle.
Smooth rev response without misfire.
No coolant leak at pump/hoses.
Recheck belt area and coolant level after heat cycle.

Uncertainty / Open Questions

Some primary sources (forum mirrors/manual mirrors) are intermittently blocked by anti-bot/cookie walls in this environment.
Public how-to sources disagree on some tool methods for crank bolt removal; factory manual method should prevail.
Exact interval guidance varies by market and service-history context; confirm in your owner/workshop documentation.

Images

No reusable images were added in this run. I could not retrieve clearly reusable/licensed NB-specific procedural images from accessible sources.

Image Credits

No images used.

Sources

BOFI Racing — MX-5/Miata Workshop Manuals - Including all Torque Settings (index of NB workshop manual PDFs by engine/year). Retrieved 2026-02-26. https://bofiracing.com/blog/mx5-miata-workshop-manuals/
MX-5 Unleashed — Changing of the timing belt (cambelt), water pump… (independent NB/NA-oriented step-through). Retrieved 2026-02-26. https://mx5unleashed.com/tech/timing-belt-mx5.html
ScegliAuto — Timing Belt Replacement (With video) (NB 1998–2005 tagged how-to summary and caution). Retrieved 2026-02-26. https://www.scegliauto.com/en/video/mazda/tutorial/4186/
The Apex Drag — MX-5 NA/NB Torque & Assembly Specs (user-compiled torque cross-reference with disclaimer). Retrieved 2026-02-26. https://theapexdrag.com/mx-5-na-nb-torque-assembly-specs/
Miata.net Forum — [NB] Timing Belt Change on Miata NB (community crank-bolt removal discussion). Retrieved 2026-02-26. https://forum.miata.net/vb/showthread.php?t=721482
Miata.net Forum — [NB 1999 1.6L] Car cranks but won’t start after snapped timing belt (community post-repair no-start diagnosis; crank trigger orientation). Retrieved 2026-02-26. https://forum.miata.net/vb/showthread.php?t=794130