Firewall leak
 

Hello all,

I'm having trouble sourcing a leak inside my CD. When washing my car or driving in the rain, I'm getting a persistent leak aft of the glovebox. I've leak tested every drain and they seem to work fine. I've checked behind the battery and there was no corrosion to speak of. I think the leak is coming from the exterior of the firewall panel (scuttle panel) and not the fresh air vents. I directed my water hose right on that metal panel around the windshield wiper and sure enough water made its way into the cabin.

I removed this panel to find water sitting there underneath the wiper motor. Is there a drain here, and if so, how do I clear it? When pouring a cup of water down in this section of the firewall, it seemed to drain fine and I think the water drain right over the transmission. However, when there is more water than it can handle it backs into the passenger side footwell.

One other thing. Water gets into this section through the cut out just above the wiper nut. When I removed the panel there was foam underneath the whole perimeter of the panel, and there seemed to be missing foam that was lining the same cut out above the hole for the wiper motor.

Could this missing foam be the source of my problem? Does it hold back water just enough for proper draining?

Someone please help.

Not sure exactly where the foam you mention goes.

The epc doesn't show anything.

I would think there is a drain, sounds as if its clogged too, but can't help in it's precise location.

Poke around in the area where it would seem logical to be.

From recollection, there are plastic drains at each windshield wiper arm. They collect water and drop in another drain at the bottom of that bulkhead. I think that the output the water from the large rubber tubes in the firewall under the hood.
My plastic drains were clogged up tight.

Correction.....they are under the air cowls too.
http://www.benzworld.org/forums/atta...k-cowl-001.jpg
[IMG]http://www.benzworld.org/forums/atta...in-circled.jpg[/IMG]

Look for rusted through holes in the tunnels that the hood springs retract into.

I suppose it is possible for it to rust through below were the Water goes in that Front Grill at the bottom of the Windshield.

Below the Battery try is another rust area, even on the Fire Wall

There are two drains in each hood hinge pocket, upper and lower. Make sure they're both free, and then check the drain in the fender liner at the rear of the front wheels.

http://i1321.photobucket.com/albums/...ps30343051.jpg

http://i1321.photobucket.com/albums/...psc376688d.jpg


http://i1321.photobucket.com/albums/...ps37ec0db4.jpg


http://i1321.photobucket.com/albums/...pse578de15.jpg

http://i1321.photobucket.com/albums/...ps63ab9daa.jpg

Check this video on you tube
Chasing Interior Water Leaks in Older Mercedes Benz by Kent Bergsma - YouTube

Kent describes this exact problem and how to cure it

Thanks for the response. I know it's hard to visualize my lengthy description. Above are some photos of the area I'm talking about.

@toomany MBZ

You can see the remnants of the foam that lines the cutout that I was speaking of. I'm sure it would help to re-foam that area. I would like to find that drain. As you can see it is blocked by the metal which supports the wiper motor.

@ytmtnman

The drains that you're speaking of work properly. Those drains are linked to the air cowls and exit out the firewall in your photos. The one I'm having trouble with is in the middle. It almost seems as if water shouldn't be in that area at all. But why would MB have that cutout? I almost want to seal it shut.

@Diesel911,rscurtis

I leak checked those areas, and they seem to be working fine.

Again thanks for the help everyone. I would love to get this problem fixed so that I can put her back on the road again. As you can see from the photos, she is starting to collect some dust.

@jay_bob

I've viewed that video three times. That was the first area that I checked. However, when I directed my water hose to those drains, no water enter into the cabin. When I poured water directly into the area in my photos, water enters the cabin.

Yes, I see the foam now. Must be part of the cover.

The tears around the wiper holes may be your problem.

If you can, source another middle panel.

@toomany MBZ

I wonder if this is specific to the 1985 CD's. I recently had a look at another 85' and he had the same cutout, but you could visually see the foam blocking it from the inside. It looks like you don't have a cutout at all.

I don't know that the torn wiper post boots would do that. Both of the boots are torn up pretty badly on my '77, and I have zero water entering my cabin.

Those smile face holes are there for a reason. I think you are missing a drain piece:
http://www.benzworld.org/forums/atta...d-dscn1059.jpg

That is it. No center drain in the photo. Water isn't supposed to end up in the center area where the wiper motor resides. Runoff from the slot under the passenger wiper post should fall directly in to that plastic drain that diverts to the left and right.