Mine was leaking badly lately. The O-ring was a little over a dollar at the local M-B dealer, and it only took about 20 minutes to remove and replace it, you do need a set of split ring pliers to get the metal circlip off- I bought some at harbor freight for $3.

Its a good idea to replace the hoses while you are doing it and not have to mess with them again for a long time.

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1991 300D 2.5 turbo
1991 560 SEL
1987 911
Toyota landcruiser
Atlanta, Gawga