GMC 1998 Transmission Problems

A leaking front seal can cause GMC 1998 transmission problems.

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.

Gear Slippage

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.

Buzzing Noise

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.

Cloudy Transmission Fluid

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.

References

• Edmunds: Transmission Problems with 1998 GMC Seirra Pickup
• "Chevrolet Silverado GMC Sierra: 1998 thru 2006 2WD and 4WD (Haynes Repair Manual)"; Ken Freund; 2008

Resources

• "Chevrolet and GMC Pick-Ups 1988-2000 (Haynes Manuals)"; Ken Freund and John Haynes; 2001