Drive belt auto tensioner leaks and rattles (TSB 01-019/19)
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What causes "Drive belt auto tensioner leaks and rattles (TSB 01-019/19)" on the Mazda Miata ND (2016-present US model years), and how is it fixed?
The tensioner's damper seal is not good enough under heat and load; Mazda changed the damper shape. Fix: Replace the auto tensioner with the revised part.
Symptoms
Oil on the tensioner body and a rattle from the accessory drive.
Cause
The tensioner's damper seal is not good enough under heat and load; Mazda changed the damper shape.
Fix (summary)
Replace the auto tensioner with the revised part.
Related build entries
Other ND problems
- Recall 19V-072: automatic may downshift unexpectedly (TCM software)
- Recall 19V-496: under-engine skid plate may detach (2016)
- Recall 21V-875: low-pressure fuel pump may fail and stall the engine
- Recall 24V-695: front airbags may deploy with too much force
- Recall 25V-336: TCS/DSC warning light may not come on
- Early ND manual: grinding into 2nd or 3rd, or gears lost (TSB 05-001/17)
More for this car
- All Mazda Miata ND (2016-present US model years) fitment answers · ND common problems
- Newsletter archive: past issues with every new and corrected entry
Sources
- Mazda TSB 01-019/19: oil leak from drive belt auto tensioner and engine-bay rattle (multi-model incl. 2016-2019 MX-5, 11/26/2019) — 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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