Bill, thanks for the replies. Driving today I kept a closer-than-usual eye on the gauge and it only jumped once, up and down maybe 2 or 3 mm. I always suspected an intermittent electrical connection, but I suppose it could be a mechanical aberration withing the gauge also.

I did have the thermostat changed about a year ago, when the car wouldn't warm up above 60 deg C except after 8 miles or so. I suspect MB thermostats are fairly variable in quality. I may just get my tech to change it along with new coolant, flush, and all new belts the next time it goes into the shop. I've been saving up my $$$ for a new steering box, and I'll have them also check the rear end for some vagueness.

thanks again Bill!

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic