Six problems related to automatic transmission have been reported for the 1998 GMC Sierra. The most recently reported issues are listed below.
Problems with transmission shifting incorrectly. While driving, the transmission became hot, and disengaged from overdrive to lock up mode, and blew 2 quarts of automatic transmission fluid out the vents.
I have a 1998 GMC z71 with 61,000 miles that I bough new and just had to have a new transmission put in at a cost of $2000. 00. When I told the serviceman what the transmission was doing he automatically new what the problem was. He said that it was the shaft housing that had busted and it messed up the whole transmission. It sounded like it was a problem that happens quite often by the way he responded. He said that the shaft housing was not as heavily built as the new one they installed. Does this mean that other owners will have the same problem with there truck around 60,000 miles? it sounds like a deffect to me if the shaft housing was not built strong enough to take the use that a truck is put through. I tow a small 5x10 utility trailer and have hauled a 27 travel trailer one time with this truck so it does not haul a lot of weight. I just hope that I do not have to have another one in about 60,000 miles. I like my truck and have payed a lot of money for it and plan to keep it.
The transmision has a harsh shift almost as if the engine mis-fires as it changes from gear to gear. Cronic has reset the electronic memory valves with no results. I am now being smoothed over by them because I don't believe they know of anything else to do. I trust that a GMC truck, number one in my book, this expensive would perform more smoothly than the competitor's truck (Ford,which outshifts GMC hands down) would. Your response as to what it is will be appreciated!! let me here from you mike brock.
Consumer was downshifting from 5th to 4th and vehicle went into reverse.
Leaks in transmission.
While driving vehicle transmission stopped shifting, also odometer/speedometer stopped working. In addition, the abs light came on while driving. Cause has not been determined.