Man its very simple, u have a crack in one of the pipes connecting to either the manifold or one of the mufflers. When water splashes the pipe cools and thus shrinks exposing the crack, as it warmes up again it expandes and the crack becomes smaller and thus less chance of it leacking.

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Jay,
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-1995 Blue W202 C36 AMG (M) SOLD ;(
-1995 Black W140 S500 (Lady)
-1992 Black W124 E300 (Dima) (Ex-Mosselman
Twin turbo Kit).
-1988 Black W124 300 E 4-Matic.(Nadeen)
-1983 Brown W126 500SEL.(Old Lady)(Sold)
-1981 Gold W123 280CE.(Dareen)(Sold)
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