← Mazda Miata NB (1999-2005 US model years) problems
Soft-top water leaks: blocked drains, side-window seals and latches
Q: What causes "Soft-top water leaks: blocked drains, side-window seals and latches" on the Mazda Miata NB (1999-2005 US model years), and how is it fixed?
A: Rain that runs off the top is collected in a rail and drains through two tubes, one on each side, whose openings sit in the corner where the top hinges, between the seatbelt tower and the body, under a flap of carpet. Fix: Clear both drains: tilt the seats forward, unlatch and tip the top back, fold the carpet flap, and feed a flexible line (trimmer line or a soft cable, not a sharp rod) down each tube, then pour in water to test.
Symptoms
Wet carpet behind the seats or in the footwells after rain or a car wash, water sloshing in the sills, a musty smell, or drips at the front corner of the top by the windshield.
Cause
Rain that runs off the top is collected in a rail and drains through two tubes, one on each side, whose openings sit in the corner where the top hinges, between the seatbelt tower and the body, under a flap of carpet. When those drains block, water pools there and can rot the sills. A club tech article covers both NA and NB. Leaks at the front corners are more often down to side-window weatherstrips that have shifted or shrunk, a clogged drain in the front seal, or top latches that no longer pull the top down tight.
Fix (summary)
Clear both drains: tilt the seats forward, unlatch and tip the top back, fold the carpet flap, and feed a flexible line (trimmer line or a soft cable, not a sharp rod) down each tube, then pour in water to test. For front-corner leaks, owners nudge the side-window weatherstrips toward the windshield so they seal against each other and the glass, and check latch adjustment. A top that still leaks may need new weatherstrips or a new top. See also the NA rust and drains entry.
Other NB problems
- NB1 ignition coil packs wear out and can damage the cat
- Thrust-bearing failure in some 1999-2000 cars
- Clutch chatter in 2001 and some 2002 cars
- Plastic radiator end tanks go brittle; airflow blockage
- Corroded coolant mixing-manifold elbow (NB1)
- Crank and cam position sensor problems
More for this car
- All Mazda Miata NB (1999-2005 US model years) fitment answers · NB common problems
- Guide: Miata NA/NB hardtop fitment guide: NA vs NB, OEM vs aftermarket, latches and seals
- Newsletter archive: past issues with every new and corrected entry
Sources
- Check those drainage holes! — MX-5 Club of Victoria (club magazine tech article, 2012) (editorial; read 2026-10-22; full page read)
- Leak in front corner of soft top — MX-5 Miata Forum (forum thread; read 2026-10-22; search excerpt only)
- DIY Projects & Tips: tops — Buckeye Miata Club (club newsletter, 2006) (editorial; read 2026-10-22; search excerpt only)
Summaries are in our own words. Not repair instructions; consult the factory service manual.
Report a correction — spotted an error or have a better source? Email hello@chassisdex.com.