you wrote: '
"""I know I could get rid of it by drilling a hole but I would like to know the source of the leak"""

searching for the leak has been covered, however "drilling a hole"...?

By Design.
You do know that there is a drain hole at the bottom of each of the rear wells. It's about the size of a half dollar coin. There is a rubber plugfixed in that hole, with a rearward facing 1/4 inch spout that is part of the plug..

In addition on the passenger side, the side with the gas tank filler that has that rubber collar around the fill spout, that too has a drain hole in it, to catch and drain away any splashed gas...there is a Tube running inside the body attached to that drain hole and it runs down to that lower plug nad is pushed thru it. It evacuates any spilled gas to the ground. People who have unexplained gas smell after filling up May find that that spill tube is just sitting in the wheel well and not shoved thru that exit port.

You should be able to see the port and the rubber plug by looking outside and under the wheel well from the outside.

What I'm saying is that there is already a hole at the bottom of the wheel well---why you can't see it and the rubber plug is another issue.

This leads to the possible source of the Leak:
If the drain from the gas filler collar has no exit the water could be draining from that collar....IF the door does not fit tight -----tho I would think that a car wash could shoot water past the door.


If this is a Sedan, there are vents along the bottom of the rear window just above the trunk. On either side, inside the trunk there are 2 drain tubes, clear vinyl about 2" in diameter that drain any water that gets thru the vent. Should exit from the upper trunk floor. That is a possible source. Check that they still exit and/or are attached. Since your leak is only on one side the drivers side would be an example of a proper set-up.

Before you get carried away talcom powdering every square inch in the trunk, do try the following basic procedure. It worked for me many years ago with my 140, which has the same trunk design.

Make a bunch of long strips of 3" wide newspaper. Lay them over the gasket all the way around the trunk (with everything dry) and close the lid. Now go around and see if any slide out easier than the others. There's all kind of reasons a trunk lid could get out of alignment, from worn hinges to a misaligned lock to a rear ender to a heavy load bending the trunk opening lip (which may well have been my case as I haul anything that will fit in the rear openingg of the car, eg. a full sized ancient Philco fridge in the case of my old 140 sedan). I found a weak gasket seal in the upper right corner of the trunk. Short of trying to re-adjust everything, try lifting up the gasket in the weak sealed areas and stuff in a spacer wherever needed to raise it up a bit. A thin piece of cord or fat piece of string is one thought, I used a long twirl of plumbers putty. Never had a leak after that.

Other possibilities include leaky taillight lenses where water can collect in the bottom of the lens cavities (a couple of 1/8" drain holes drilled at a steep up angle can fix the problem until you get around to resealing the lens seams). Another would be if you had a sunroof and the rear drains are blocked with debris -if you've got a sunroof that would actually be my prime suspect -see the 700/900 FAQ for dealing with sunroof drain issues.

Please post back with how you make out.

[I've been trying to reply to your post for a few days now, but Jarrod's fiddling around with the site has seemingly been in my way, hopefully this reply will stick]

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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Sources of water:

#1 Rear tail light lens. Just pulled out. Cleaned out old gunk. Resealed with RTV.

#2
After knocking and cutting the weak stuff:


Fixed. Inside had to look good for the spare tire.


#3? Not sure but I think water would be found on the rear floor.


I have some rusting at the left rear piller. Not shown in the picture. From where?

Tom

Check the tail light assembles especially along the bottom edges inside the trunk.

The best method I have found to find leaks. Pull everything out, dry it all. Get some cheap baby powder/talc. Sprinkle/throw on all the vertical surfaces. Close the trunk and garden hose time. Where it is coming in will leave a "snail trail". Good luck.
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Post Back. That's whats makes this forum work.