450SLC wet feet

I’ve had a problem with wet feet in my 450SLC for years.   Generally this manifests itself with water dripping onto both the drivers and passengers feet when the A/C is running.   This is particularly prevalent when going around a corner.   I had always assumed that this was caused by blocked A/C drains.   I tried to clean them a couple of years back but the problem never went away.

A couple of weeks ago I took the car on an extended drive and had a lot of water covering my feet, but especially in the passengers side.   I figured it was time for another go at fixing this.

My first step was to remove the dash underside and see if the drains were still connected.   My previous attempt to clean the drains was from the underside of the car.    I was immediately presented with a rats nest of wiring and two old amplifiers.   The Becker amp even had the first owner’s name (Fletch).    The Becker radio is long gone, but the old amp was still there in the dashboard.   I guess Ian Fletcher (Fletch) had the amp repaired at some point.   This was a good opportunity to clean up all that old wiring.

The drains did seem to be connected. The insulation for some of the pipes and valves had dropped down, but I don’t think that would be enough to create that much water.
As part of getting the side carpet back, I removed the carpet and insulation padding from the passengers side. It was soaking wet.

I use rubber floor mats in the 450SLC, so I hadn’t noticed how wet the carpets were on this side. Surprisingly, they were not wet on the drivers side. Unfortunately, the wet carpets have caused some surface rust on the floors of the car. I will have to grind this back and treat it.

As I hadn’t found anything obvious,  I decided to run the car for a while with the A/C on and see what happens.   This test was also somewhat inconclusive.    A ran the car for about 30-40 minutes with the A/C on.   I got no water in the car at all.   It also took at least 10 minutes to get condensate dripping out of the A/C drains.   The dripping was not as much as I expected and was only from the passengers side.   I put the car up on the hoist and tried to clear the drains with a metal rod covered with a plastic sheath.   I wasn’t able to free any water so not sure if I really did anything here.

My current theory is that the A/C drains drains are somewhat blocked.   This allows the evaporator case to fill with water.   As I drive around a corner, some drips on either the drivers or passengers side depending on the turn.   I don’t think this is enough to totally saturate the carpets, so I think I have a rainwater leak too.   I will need to do more work to isolate both and to treat the surface rust.