The 1998 GMC Sierra is a full-size pickup truck manufactured by General Motors. Renowned for durability, the 1998 GMC Sierra can, however, experience transmission problems that often can be resolved via some basic troubleshooting checks.
If the gears slip on your 1998 GMC Sierra, a leaking front seal, which normally keeps the transmission fluid that flows to the transmission from the converter from leaking out, may be to blame. Inspect the front seal for wear and damage, and replace it as needed.
A buzzing sound emanating from your 1998 GMC Sierra can result from a bad torque converter, which is the coupling located between the transmission and engine that enables idling at low rpm. Check the torque converter by putting the gear in drive and then applying light pressure on the gas pedal. If the buzzing noise occurs or you feel vibrations, the torque converter is bad and should be replaced.
If you check your 1998 GMC Sierra transmission fluid and notice cloudy or milky residue on your dipstick, your fluid is either old or of poor quality and should be replaced. Flush the transmission and add high quality transmission fluid to correct the problem.
