Mazda MX-5 NB
Weaknesses, engine ratings and buying advice
The MX-5 NB (1998-2005) is the second-generation Miata — sharper than the NA, lighter than the NC, and at 21-27 years old in 2026, a car where rust kills more examples than engine failure ever will.
Two engines, one clear favourite: the BP-ZE 1.8L in NB2 form (2001+) gained variable valve timing (S-VT), better crank bearing support, and a revised exhaust manifold. 143-146 hp depending on market, dramatically better mid-range than the pre-VVT version. The pre-VVT 1.8 (1998-2000) uses oil as a personality trait — manageable if checked, catastrophic if ignored. Running any NB low on oil has thrown rods. The B6-ZE 1.6L is lighter, revvier, and beloved for track use — 80,000+ mile examples still pulling like new. Less power (110 hp), more character, cheaper insurance.
Both engines are interference designs with timing belts. Replace every 5 years or 54,000 miles — not the commonly cited 60,000. On a 20-year-old car, even a “recently changed” belt may be overdue. Budget £200-400 / $250-500 for a full belt + water pump kit if history is uncertain. This is the single most common deferred maintenance item on any NB.
The #1 killer: rust in the front chassis rails. The NB's double-skinned front frame legs are a notorious trap where terminal corrosion hides behind the plastic undertray. Remove it and look with a torch before signing anything. Cars pass inspection with seriously compromised rails because the damage is invisible from above. Sill perforation was documented on cars as young as 5 years old in the UK. If the car feels vaguely floaty despite fresh bushes — the chassis has lost rigidity.
Coil packs deteriorate with age — cylinder 4 fails first. Misfires under load, P030x codes. Replace all four preventively (~$120-180). The ignition switch also wears, causing extended cranking. Rear brake calipers seize on low-use cars (~$140 per side).
Test-drive checklist: Cold start: cambelt rattle in first 2 seconds? (timing). NB2: VVT rattle at idle? (oil pressure actuator). Oil filler cap: mayonnaise = head gasket. Every gear: 2nd and 3rd synchro wear on driven examples. Handbrake: actually holds? Soft top: check rear rain rail for cracks — water pools and rots the floor from below.
2026 market: Average solid driver $4,000-$7,000 / £2,000-3,500. Clean NB2 Sport (Torsen LSD, Bilsteins): $8,000-$12,000 / £4,000-5,000. Mazdaspeed NB turbo: $10,000-$18,000 (collector territory). Insider pick: NB2 1.8 Sport (2001-2005) with VVT, Torsen diff, documented cambelt, and a rust-free underbody — the most complete driver's car of the NB run without the Mazdaspeed turbo complexity.
Generations
Engine Overview
The Mazda MX-5 NB is available with 2 engine variants — from 110 to 145 hp.
1.6 litre 16V, 110 hp — the lighter of the NB engines. Sharp and nimble, needs revs for fun. Below 4,000 rpm it's docile; above that it comes alive. Hydraulic lifter rattle on cold start is normal as long as it disappears once warm. Crank angle sensor and thermostat are the most common failures. Timing belt every 90,000 km or 6 years — interference engine, snapped belt means engine damage. Oil change every 7,500 km. The 1.6 in the NB is the purist's choice: lighter, forces commitment, rewards it.
- !! Short-Nose Crankshaft — Pulley Damage from Incorrect Torque
Early NA6 models up to chassis number 127442 (before Sept. 1990) have a delicate short crankshaft nose. Incorrect torque (160 Nm instead of 112 Nm) or fitting the key incorrectly during a timing belt change destroys the crankshaft nose. Total engine failure possible.
Symptoms: Pulley wobbles or runs out of true, rough engine, vibrations from the front end, timing belt snaps - !! Valve Clearance Check Required from 90,000 km
Bucket tappets without hydraulic compensation require a valve clearance check every 90,000 km. Excessive clearance leads to burnt exhaust valves and power loss.
Symptoms: Ticking noise from the valvetrain, power drop, rough idle - !! Thermostat Stuck Open — Engine Fails to Warm Up from 100,000 km
The B6-ZE thermostat can stick in the open position, preventing the engine from reaching operating temperature. Engine stays cold, heater output drops, fuel consumption rises. Use OEM thermostat opening at 88°C instead of aftermarket units opening at 82°C.
Symptoms: Engine never reaches operating temperature, temperature gauge stays in the lower range, heater blows cold air, increased fuel consumption
+ 6 more engine weaknesses + vehicle weaknesses
1.8 litre 16V, 140 hp — the grown-up NB engine. More torque than the 1.6, more relaxed without losing the NA character. NB2 (from 2001) with VVT: 146 hp and dramatically better mid-range — the strongest factory engine of the NA/NB era. Hydraulic lifter rattle on cold start, thermostat sticking — classic NB issues. Oil pressure switch leaks from 120,000 km. Timing belt every 90,000 km is non-negotiable. Rust on the front sill rails is more dangerous than any engine problem — if those are gone, the car is gone. Buying rule: check the underside before the engine.
- !! Crankshaft Thrust Bearing — Wrong Part in 1999/2000 Build Year from 65,000 km
In NB models built 1999–2000 (up to approximately chassis number XY), Mazda fitted undersized thrust bearings. The crankshaft has too much axial play and knocks against the bearing when the clutch is pressed. Mazda replaced affected engines under warranty, but unmaintained used cars may still be affected.
Symptoms: Knocking or grinding noise when pressing the clutch, disappears when clutch is released, crankshaft shows axial play over 0.3 mm - !! Valve Clearance Check Required from 90,000 km
Same as the B6-ZE: bucket tappets without hydraulic compensation. Valve clearance check every 90,000 km is mandatory. Excessive clearance leads to power loss and valve damage.
Symptoms: Ticking valve noise, rough idle, power loss - !! Water Pump Leaking from 100,000 km
Water pump leaks at the gasket or shaft bearing. Ideally replaced together with the timing belt, as it is driven by it.
Symptoms: Coolant loss, overheating warning, coolant puddle under the engine
+ 6 more engine weaknesses + vehicle weaknesses
Vehicle Weaknesses
| Weakness | Cost | |
|---|---|---|
| Longitudinal members and sills rust through Front longitudinal members and sills rust from the inside out through unsealed panel flanges. Structural concern: the sills can lose their jacking points and strut tower attachment. Repair costs €1,500–3,500. Symptoms: Rust visible on the bottom edge of sills and around the front axle; vehicle can no longer be safely jacked up; MOT defects from 80,000 km | High |
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All Mazda models Known Problems and Issues +
A total of 27 weaknesses have been documented for the Mazda MX-5 NB (1998–2005) — 18 engine-related and 9 vehicle-related. Typical issues affect Rust, Body, Electronics, Brakes.
MX-5 (B6-ZE, 1998–2005) — Be Careful: Short-Nose Crankshaft — Pulley Damage from Incorrect Torque, Valve Clearance Check Required, Thermostat Stuck Open — Engine Fails to Warm Up. Power: 110 PS.
MX-5 (BP-ZE, 1998–2000) — Be Careful: Crankshaft Thrust Bearing — Wrong Part in 1999/2000 Build Year, Valve Clearance Check Required, Water Pump Leaking. Power: 139–145 PS.
What to watch out for with the Mazda MX-5? See the detailed listing of all engine and vehicle weaknesses in the sections above.
Frequently Asked Questions
What problems and weaknesses does the Mazda MX-5 NB have? +
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Last updated: February 2026 · All information without guarantee