The only option is to repair your leaky plastic housing. There's a thread here somewhere that I posted. Get a radiator repair kit from an auto parts house and use the fiberglass and epoxy to make a bandage for the monovalve. It will be much easier if you completely remove the monovalve/pump from the car, take it apart, and clean it thoroughly. However, if you are in time pressure you can do the repair in place. Warning: the radiator repair kit ($20) epoxy sets up in a minute or two, you must work quickly!

My repair is over three years old now and has never leaked. New assemblies are terribly expensive and will also leak after a few weeks—I went through three before repairing my leaky valve and returning it to service. After three years of polite insistence, Mercedes finally refunded the $500 I paid for the first replacement (the others were warranty items).

Jeremy

__________________

"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