Three problems related to manifold/header/muffler/tail pipe have been reported for the 1999 GMC Sierra. The most recently reported issues are listed below.
Two broken manifold bolts in rear drivers side of engine on 5. 3 vortec engine, exhaust leak from where manifold has separated form head. Carbon buildup and discoloration visible. High temp exhaust being released under the hood. Appears to be a very common complaint on many gm vehicles and model years.
Faulty braking system engine noise muffler replace instrument panel fault tire wear transmission automatic shifting rearend noise.
Fuel pump will over heat and than short out. Exhaust always rattles engine knocks cat. Converters went out digital display stopped working.