Funny you bring this up...my 240Z is at the body shop now, and I suspect mine is also clogged, there's a tube that exits outside the body in front of the passenger side, thought it was related to my A/C but I think it connects to the main cowl drain outlet, I'm planning to "snake" it from there, access through the cowl may be difficult...maybe slightly different on the 280...need to check this over the weekend..
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