Coolant mark at the water pump bleed hole is usually normal
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What causes "Coolant mark at the water pump bleed hole is usually normal" on the Mazda Miata NC (2006-2015 US model years), and how is it fixed?
The pump's mechanical seal lets a little steam out of the bleed hole when the seal face runs above about 120°C; it dries to a mark. Fix: Mazda says not to replace the pump for a mark alone, only if crystallised coolant builds up around the hole (TSB 01-004/09).
Symptoms
A small coolant-stain mark at the water pump bleed hole.
Cause
The pump's mechanical seal lets a little steam out of the bleed hole when the seal face runs above about 120°C; it dries to a mark.
Fix (summary)
Mazda says not to replace the pump for a mark alone, only if crystallised coolant builds up around the hole (TSB 01-004/09).
Other NC problems
- Recall 06V-103: driver airbag horn-assembly bolt (early 2006 cars)
- Plastic coolant expansion tank cracks and dumps coolant
- Plugged soft-top drains put water in the footwells (2006-2009 TSB)
- PRHT crunches or is hard to open (2007 TSB 09-038/07)
- PRHT windshield header and roof rattle (2007-2008 TSB 09-035/08)
- PRHT front roof panel contacts the deck when open (2007 TSB 09-035/07)
More for this car
- All Mazda Miata NC (2006-2015 US model years) fitment answers · NC common problems
- Newsletter archive: past issues with every new and corrected entry
Sources
- Mazda TSB 01-004/09: replacement of water pump for coolant leak — bleed-hole steam mark is normal (multi-model incl. 2006-2009 MX-5, 02/03/2009) — Mazda North American Operations (service bulletin) (mfr spec; read 2026-10-26; full page read)
Summaries are in our own words. Not repair instructions; consult the factory service manual.
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