W123 300D - Two questions -Electrical and chassis

[Graham]

I am starting to reassemble after rust repairs and have two questions:

Electrical - There are three thin black wires coming out of chassis in front of passenger side door. One is disconnected. Anyone know what those wires are for and where they connect?


Chassis - Under the floor pans in front of car, there are two chassis beams that go forward to the engine area. These beams have holes in them. Does anyone know if there were rubber plugs in those holes?

(Some of rust on my car was directly above those holes, so I am likely going to put plugs in.)



Finding which plugs go where is always a challenge. (see separate post_

[BillGrissom]

I'll verify on mine when I get home and report if untrue, but I don't think you want plugs in the bottom "drain" holes of the front frame rails. My Mopars don't have plugs there. Had they been plugged, I doubt the factory undercoating would go to and beyond the edge of the holes as shown in your photo.

Even better if you can spray rust converter inside the frame rails. I heard that Eastwood has a remote spray tip for that. I painted the inside of mine in my Dart when I had the innards better exposed during a floor pan replacement. I think Mercedes frames were fully painted (tank dipped) in 1985, so probably no need, at least where I live.

[Graham]

Originally Posted by BillGrissom

I'll verify on mine when I get home and report if untrue, but I don't think you want plugs in the bottom "drain" holes of the front frame rails. My Mopars don't have plugs there. Had they been plugged, I doubt the factory undercoating would go to and beyond the edge of the holes as shown in your photo.

Even better if you can spray rust converter inside the frame rails. I heard that Eastwood has a remote spray tip for that. I painted the inside of mine in my Dart when I had the innards better exposed during a floor pan replacement. I think Mercedes frames were fully painted (tank dipped) in 1985, so probably no need, at least where I live.

I would be interested to hear if you and others have those open holes. Can't see much down side of having them closed and respraying annually with rust preventative.

The inside of those rails had the original typical Waxoyl type coating. Probably over paint. But nevertheless, my floorpan rusted out very badly directly above one of those holes. That has all been repaired and everything will soon be rust sprayed . (Something we do up here, but it obviously didn't work in those rails!

[Graham]

Originally Posted by BillGrissom

I'll verify on mine when I get home and report if untrue, but I don't think you want plugs in the bottom "drain" holes of the front frame rails.

Just wondered if you did check?

I can see there would be no need in dry climate, but in ours, I think I want to plug those holes and at most provide a smaller drain hole that salt will have difficulty getting in.

[vstech]

plugging the holes would be a bad idea.

the rust you have was more than likely caused by water inside the car sitting under the soundproofing under the carpets.

[Graham]

Originally Posted by vstech

plugging the holes would be a bad idea.

the rust you have was more than likely caused by water inside the car sitting under the soundproofing under the carpets.

You could be right. But I would be interested to know the reasons you think it would be a bad idea. This given that we drive in salt covered roads for 5 months of year and salt would definitely collect inside those beams. It collects everywhere else! We can wash the bottom the car off, but not so easily inside those beams.