No noticeable loss of coolant. I was hypothesizing at the end of the post that had it been leaking coolant into the cylinder it would have had hours to leak past the rings, and, if it did that, it would have started to leave evidence on the dipstick and oil cap that there was a significanct amount of water in the oil. But no, my car was merely swallowing a quart of oil every 100 miles all of the sudden. It had always used about a quart every 5000 miles before and then it developed a growing thirst. In a matter of a few months and maybe 3500 miles it was consuming a quart in less than a tank of fuel. But I never had a coolant consumption/loss issue during this episode. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)