I've just noticed a whitish- stain trail down the neck of my radiator neck on a M104 with 203,000 miles. Is this the start of the much publicized neck failure? Is it catasrophic, causing road side break down or gradual, just making a mess?

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dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles

It's my understanding that it usually happens very suddenly. The neck just cracks and separates without any warning at all. On a car with that many miles, it's probably a good idea to just replace it as a matter of preventive maintenance.

I bought my 86 300E a year ago last June with 94,000 miles on it, and the neck had already broken and been repaired with JB Weld and a piece of copper pipe. I replaced it with a new Behr radiator with the metal reinforcing sleeve in both hose necks and replaced the standard MB anitfreeze with Evans NPG+ coolant and I've had no sleepless nights for the last 30,000 miles worrying about it.

Gary