I had one on my '85 300D (W123, OM617) that worked great although I didn't need it very often. It was a superior alternative to the factory block heater, because the trap catalyst made the installation point almost impossible to reach.

Most radiator hose heaters draw more power than the Mercedes in-block heater, 600 Watts vs. 400.

Remember to take lattitude's advice and replace the entire radiator hose. Put the old one away in the spare tire well as an emergency spare. Route the electric cable carefully so it won't foul the fan.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970