Drain Hole Under Brake Booster & Wiper Motor

[Joe]

Got the brake booster off to paint, and decided to remove the cast bracket for cleanup. I then noticed a drain hole under these parts. This hole had a decomposed rubber part in the top. I ran a cable down the hole, and it came up with rusty water on it. However, I could not find the exit for this passageway.
Should there be some sort of grommet at the top?
Where is the exit?
Any help is appreciated.
Joe

[rwmastel]

I believe this hole, and the corresponding one under the radiator expansion tank on the other side, drain directly to the wheel well.  Drop a small screw driver in there and look from underneath with a flashlight.  See threads
http://index.php?topic=375
http://index.php?topic=187
about drain holes.

Rodd
1966 230SL Euro
1994 E420

[Joe]

Well, thanks for the advice, Rodd. I did find those two holes, and they were, indeed clogged up. However, they are not the hole I was describing. This hole is under the casting which fits between the firewall and the brake booster. It cannot be seen with the casting in place. There is an identical one just under the windshield motor. This one has a grommet in it, and I think the other one did, too, but leaking brake fluid destroyed it.
It seems strange that drain holes would have grommets in them. Does anyone know what these holes are? Like I said, I ran a cable down into the one on the left side, and it came out with rusty water on it.
Joe

[rwmastel]

Joe,
I just went out and looked.  My grommet under the windshield wiper motor seems to have a bottom to it.  Perhaps these are plugs?  I found the one under the area where the brake booster bracket mounts to the firewall.  That rubber was distored as yours must be.  I don't know if these should be rubber grommets or rubber plugs.  Anyone?

Rodd
1966 230SL Euro
1994 E420

[Ricardo]

I think these could be factory undercoating access holes, used to spray into the firewall crossmember after it was welded to the firewall. If so they would likely be plugs, though they could have originally had a slit in them. I thought mine did when I replaced the firewall crossmember and wondered if the rubber grommet/plug was supposed to be a vent with a raised rim to prevent water running in, but allowing moist air out? The holes were there on the new crossmember.
Richard V

[rwmastel]

http://index.php?topic=375

Please post all drain hole comments to the above thread to keep them all in one place.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Naj ✝︎]

This has come up before.
It goes into the cabin. Mine had also deteriorated beyond recognition but it should be a plug similar to the one under the wiper motor.
Now, whats the part # for it?
I've not been able to find a suitable plug yet!
naj

65 230SL
68 280SL