I purchased a 1998 Olds LS Vin k 3800 series 2 and the owner had a tap that we thought might be a lifter. The tap got louder and not long after I had to have the engine replaced because apparently he had the repair done to the intake manifold a little too late and coolant had destroyed the rod bearing. That little coolant leak isnt enough to usually cause much of a problem so it goes undiagnosed for a long time. Meanwhile there is a small amount of coolant mixing. *Otherwise* one of the best engines ever.