When we got our 1988 300TE in 1996, on our first long trip (Big Bear @ 102F), the heater-hose between the firewall and the rear engine sprung a leak. Various MB mechanics have told me this a prone area (lots of heat, and stress when pulling the oil-filter), so I have spare with me.
Of course, it was a Sunday afternoon, so we had to improvise with parts from NAPA.
Soon afterwards, the upper radiator neck cracked (original radiator, did not have the metal reinforcement sleeve).
That's when I decided to replace all hoses, the radiator, and the waterpump (105K miles). I also did a degreasing and citric acid flush. I also learned that you do not overtighten the clamps (the German hose clamps while not cutting into the hose, are too narrow and don't spread-out the force). I use a 1/4" flexible-spring drive, and when it deflects, I stop tightening. Also, you don't periodically tighten the hose clamps.
Fill only with distilled-water 55% and 45% MB antifreeze plus a bottle of RedLine Water-Wetter. Yes, distilled-water is corrosive, but NOT when mixed with antifreeze. MB recommends soft-water, and here in Santa Barbara our water is way too "hard."
I flush, every two years, and every 6-months check the PH with PH Coolant Test Strips from NAPA.
I believe by keeping the PH as close to virgin MB antifreeze which is more neutral than the "green stuff", longevity can be had.
Now even the steep grades to Las Vegas at 110F or a full 5-hours of wide-open throttle at Willow Springs barely bring s the temp above 90-C.
Best of luck,