help wanted finding where leak is coming from under dashboard

[rutger kohler]

Hi, I am re-assembling my 280SE after a full bare body resto. Working on putting the dashboard back together and have found a hole in the firewall under the dashboard that leaks rainwater.  It is nothing to do with the water drained away from the trays under the windshield wipers etc, I have checked both the drain tray and the drain pipes and they are fine.  It looks to me like someone has drilled a hole for something, in the past?

To orient your view this is a right hand drive car. The photo is taken looking up under the dash, however when I attach the photo to this file it repeatedly rotates 90 degrees so you will have to rotate it back 90 degrees in your viewer, or look at the photo sideways sorry.

Doing this, to the left you can see the heater/vent box and to the upper right, the steering column.  The hole is easily identifiable as you can see a stain coming from the hole. Should I simply plug the hole, and if so where is the rainwater coming from?

[Tyler S]

If its not a factory hole then I think your best bet is plugging it.
The water may be entering through the hood gap and traveling down the front side of the firewall along some wires or piping.
See if you can insert a piece of wire or a small stick to help you locate it on the engine side.