# NHTSA Engineering Analysis EA01013
> **VACUUM BRAKE BOOSTER FAILURE** · Opened 2001-05-22 · Closed 2002-12-15
## Investigation
- **Action number:** EA01013
- **Type:** Engineering Analysis
- **Open date:** 2001-05-22
- **Close date:** 2002-12-15
- **Manufacturer:** General Motors, LLC
- **Affected makes:** CHEVROLET
- **Affected components:** SERVICE BRAKES, HYDRAULIC
- **Affected model years:** 1997, 1998, 1999, 2000
- **Affected (make, year) variants:** 4
## Summary

ODI UPGRADED THE PRELIMINARY EVALUATION TO CONDUCT A FULL TECHNICAL ANALYSIS, INCLUDING TESTING.THE TESTING AND ANALYSIS SHOWS THAT A TORN DIAPHRAGM IS A SLOW PROGRESSIVE TYPE OF FAILURE.THE TEAR PROPAGATES IN A SLOW METHODICAL MANNER AND BRAKING PERFORMANCE IS SIMILAR TO AN UNTORN UNIT UNTIL THE TEAR EXCEEDS 1/2 INCH.ODI'S TESTING INDICATES THAT TEARS GREATER THAN 1/2 INCH REQUIRED INCREASED PEDAL EFFORT.HOWEVER, AS THE LENGTH OF THE TEAR INCREASED BEYOND 1/2 INCH, A HISSING SOUND COULD BE HEARD EMITTING INTO THE PASSENGER COMPARTMENT WHERE THE MASTER CYLINDER PLUNGER PASSED THROUGH THE FIREWALL. ODI HAS DETERMINED THAT A SAFETY-RELATED DEFECT TREND HAS NOT BEEN IDENTIFIED AT THIS TIME AND FURTHER USE OF AGENCY RESOURCES DOES NOT APPEAR TO BE WARRANTED.THE CLOSING OF THIS INVESTIGATION DOES NOT CONSTITUTE A FINDING THAT NO SAFETY-RELATED DEFECT EXISTS.THE AGENCY RESERVES THE RIGHT TO TAKE FURTHER ACTION IN THE FUTURE IF WARRANTED BY THE CIRCUMSTANCES.ODI'S COMPLETE TECHNICAL ANALYSIS WITH TEST DATA IS ATTACHED.

## Source
- [NHTSA ODI investigation page](https://www-odi.nhtsa.dot.gov/owners/SearchResults?searchType=ID&targetCategory=I&searchCriteria.nhtsa_ids=EA01013)
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