A/T - 440-T4 Modulator Valve Making Buzz Noise
87cad6Bulletin No. T 88-12
File in Group 7
Number 172
Corp. Ref. No. 777138
Date Sept. '87
SUBJECT: MODULATOR VALVE BUZZ NOISE - THM 440-T4
MODELS AFFECTED: 1986-1987 DE VILLE, FLEETWOOD, ELDORADO AND SEVILLE
Some 1986-1987 De Villes, Fleetwoods, Eldorados and Sevilles equipped with 440-T4 transaxles built prior to February 1, 1987 (Julian Date 032), may exhibit a buzzing noise from the transaxle.
This buzzing sound may be caused by a missing orifice cup plug in the modulator circuit of the channel plate. This orifice cup plug was required with the change to the altitude compensated (aneroid) modulator.
FIGURE 1 - ORIFICED CUP PLUG:
To repair this condition, remove the transaxle and channel plate and insert the cup plug from the service package listed below (See Figure 1). Press the cup plug flush to .5 mm below the surface.
Part Number Description
8646987 Service Package: Orificed
Cup Plug, Lower and Upper Channel Plate Gasket, Modulator Port Gasket and Instruction Sheet
For warranty purposes, use Labor Operation number K7460 for C-Car at 5.5 Hours and E/K Car at 6.1 Hours.