One problem related to blown head gasket has been reported for the 1998 Buick Lesabre. The most recently reported issues are listed below.
I purchased a '98 Buick Lesabre - from my brother-in_law, it only had 70,000 miles on it when the head gasket blew causing me to rebuild the top section of the motor--then after that was fixed and I drove the car for approximately 3 months more -- the bottom part of the engine blew--and I had to replace the complete engine not knowing what caused this problem. The car was always maintained by the dealership "boyle Buick" in bel air, MD.