Help needed tracing water leak in cabin

[rutger kohler]

Several weeks ago I took my 280 SL RHD drive on a rally, during which time it rained.  Several days later I was dismayed to see a rusty trail inside the cabin, under the dashboard to the left of the steering column (see photo, should this hole be here?). The car is in very good shape and never leaked before.  I immediately suspected the drains from the cabin air intake were blocked and rain had collected and spilt over from there, however I have checked these and the leak did not come from there.

Looking in the enginebay, on both sides immediately in front of the firewall I have noticed what looks like two factory made holes (see photos) about 10mm diameter. These appear to let into the hollow cross member under which the leak came from.

What is the purpose of these holes? Are they supposed to be open and if so where should they drain to plse?

ps as usual I have loaded the photos in the wrong order

[rutger kohler]

Have just found how to make arrows on paint so I am re-posting the two enginebay photos with red arrows pointing to the holes.

[jameshoward]

Have you checked the hoses that from from the air intake/firewall area to the drain plus you show in your photos? Pour some water in through the air intake area (a little) and see if you get any seepage inside the footwell. That would seem the first place to look and the most likely culprit. You can chech the condition of the hoses by removing the card under the dash. Remove those before you pour the water in so you can see. 

[gnj588d]

I had the same problem a few years back.Water was getting in through a redundant screw hole on the crossmember under the hood {hidden by the cable}
water ran from the hood gap into the screw hole and filled the crossmember full of water until  it reached the screw hole inside the cabin and overflowed
into the cabin  soaking the carpets.Cheers.Mike.

 

[rutger kohler]

Hi thanks for those replies.  James, I have checked the hoses, took them off and made sure everything was clear.  If the hoses leaked they would leak directly into the cabin, not through the cross member.  Mike, what did you seal the holes up with. Are my holes factory made, and if so what is the purpose of them?

[gnj588d]

I used a small rubber grommet with some silicone sealant,the holes look original but could not say for sure.
I also drilled a small hole each end of the crossmember under the fender and sprayed waxoyle inside,
then fitted two grommets which can be removed easily.Mike.
 

[andyburns]

Hi Rodger,  take a  look at the photo attached.  When I prepared my engine bay I remember the two main drain holes being well blocked up with 40 years of muck.  All the water that comes down the windscreen that flows into the gutter at the top of the engine bay would end up down on the top of the box section you refer to.  If the water cant escape down the main drains quicker than it coming in then it would back up on the box section and flow into the additional holes.  I think looking at the photo and the holes on my car they are probably put in as an additional last bastion for water to escape.   Am going to have a good look at somehow closing mine in as well as I definitely dont want water inside the box.  I sprayed a can of brunox into the box section using these two holes if my memory serves me correctly.

[tel76]

The two holes that are in your picture should have rubber bungs inserted.