Transmission problems have been identified for every model produced by Buick, though some years have fared better than others. The problems reported vary from transmissions shifting erratically and loss of transmission fluid to transmission failure. There are also some other problems reported in Buicks which may be mistaken for transmission issues, such as potential looseness in the throttle pressure cable connecting the carburetor to the transmission in several models.
Buicks with 440T4 / 325 4L transmissions may exhibit shortened lives if the attached modulator is not maintained. The condition of the modulator may be checked by pulling the attached vacuum line from its connector to the transmission; fluid in the line indicates a bad modulator. Since modulators control shift firmness, a bad modulator can result in slipping gears.