W210 '99 e300 headlights (replaced ones)leak
 

ok, i put a '00 pass side headlight on my w210, and i also bought used one w crack where the turn signal goes in, and after a good car wash the both started to leak and water got in my heads and high bemas also

what could cause this any ideas?

headlights from 00 do not fit the 99 model year as they were to distinctively
different designs though under casual glance, appear same.

insofar as leaking, you say you bought a used headlight with a known defect.
water intrusion occured. I don't know why you're asking if for ideas as to
the cause....as the answer seems quite apparent.

yes but the idea is what path does the water that drains down take, to get into my hlamps, both of them have good amount in them,

could it be a rubber seal leak around the headlight

It's not the black rubber trim piece, but the seal between the lens and the headlamp body. You may be able to take it apart and reseal it.

When you go to fix it, make sure there is zero moisture in there because once you seal it with silicone or whatever, any moisture in there is trapped. Also, inspect the bulb sockets for corrosion carefully, and if the bulbs are HID, wipe them with an alcohol soaked lint-free rag.