If you've been driving the car and the engine hasn't blown up you're probably OK to continue as-is. To be absolutely sure, connect the hose that runs behind the engine to the hose that goes into the thermostat housing. Leave the two heater hoses capped.

You may have to pull the battery and battery pan to see which of the three hoses runs behind the engine. Two of the hoses go into the firewall and lead to the heater core (the same heater core is used in cars that have dual controls, hence two outlets). The third hose connects to a pipe that runs behind the engine and connects to the head.

On the forward end of the valve/pump are two hoses. The little one can be left capped -- it feeds the windshield washer bottle heater. The larger hose is the return-to-thermostat hose. Connect it to the one that runs behind the engine. That will allow coolant to flow from the head back to the thermostat and on to the radiator. May not be necessary but who knows.

If you figure out a repair please share. MBUSA has asked me to have my dealer contact an MB rep to come see the leak with the part still in my car. Maybe there was a defect in the manufacturing process.

Jeremy

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"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