I had a leak in that area and it turned out to be the reaction valve seal. Discovered it by cleaning up really well, driving a bit, then taking a look.

So re-build instead of re-seal? Maybe a re-seal with that kind of high mileage is throwing good money after bad.

How quickly are you losing fluid? I sure would be tempted just to keep pouring fluid in....

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife