240Ed,
I found that the water on the hood release comes from either the windshield corner or where the door's rain gutter drains into the engine compartment. I ran a bead of 'Permatex' flowable windshield sealer along the rain gutter and the winshield corner, letting it flow down into the engine compartment and my 240 no longer leaks there. I also sprayed the area under and behind the hood springs with 'Bluemagic' rubber undercoat. The rubber drains in the wheel wells also need to be cleaned out. The heater intake drains are on the front of the firewall. Don't know about the A/C drains. Use the search to find other posts about my experiences with water leaks.
Good luck, thebern

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1982 240D 313,000 (4 speed)
1984 300CD 172,483
1985 German Shepherd Dog -Lacey- R.I.P.11/04/05

Hood Stars, Wrist Crowns and Obsession Dobs