Both my Dad's 1995 M104 water pump and my M103 water pump failed at about 170K mi here in FL. Based on that and my current practice of driving more on long distance trips I replaced my M112 pump at 170K mi. I used a dealer rebuilt pump on the M103 and Grafs on the M104 and M112. No problems with any of them. I would much rather replace a part like this at my convenience than have to deal with the headache and cost of replacing while on a trip. Further, if the pump should manage to fail suddenly you may miss the high temps and fry your engine. Just my $02. It's interesting that years ago (60's in my personal experience) MB would specify replacement schedules for major components such as water pumps, generators and suspension components. IIRC the W112 300 series air suspension bellows were to be replaced at 100-110K kms with a set age limit as a kicker. Sure, you could get a little more life out of these components but not that much more that the risk of breakdown was worth it. Mark