Very odd corrosion failure of the vacuum box (vacuum modulator).

Symptoms:

* Over the past year, there has been a steady progressive power loss.

* This evolved over the past three weeks into a hyper speed Hammering up shift = hitting fourth gear at 24 - 28 MPH.

* Once in fourth gear, it would not kick down.

The leaking vacuum modulator was diagnosed and a new part ordered from the local dealer Tuesday of last week, and the part arrived seven days later..

During removal, the old unit steel band crumbled, as displayed in the following pictures.


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After installing, and adjusting the new unit..

The test drive left the owner with a giant GRIN.

The Hammer and hyper shift are gone.
The missing power has returned.
Kick down is flawless.



.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

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