Body/Trim: 140: Water in the trunk

[142 Guy]

I figured that if anybody would be in the know about water ingress issues in a 140, it would be UK owners so here goes!

I did a fairly extensive resto on my 1971 142 which included replacing both wells in the trunk behind the rear wheels. The reproduction wells came with flat spots where the rubber drain grommets / plug things would be located; but, no hole for the plugs. Those holes had previously required constant rust maintenance on the car, so I decided not to cut them open, in part because the trunk was getting a new gasket and the panels would all be aligned and everything (almost everything as it turns out) was going to be re seam sealed. As such the trunk should be dry, right?

Shortly after getting the car back together, I discovered that the trunk was accumulating quite a bit of water in both wells after heavy rains and car washes. Water does not appear to collect anywhere else in the trunk. The tank area remains dry. Testing with a garden hose and checking showed that the biggest source of water was from around the drain box for the extractor vent under the rear windshield. During the resto work we had missed the fact that the seam sealer at both ends of the drain box (above where the drain hoses attach) had contracted and pulled away from the body allowing water to drain out the ends and into the trunk. It was a pain to fix with the car upright (it would have been so easy when it was on the rotisserie); but, I pried off the original seam sealer and completely resealed the box. Subsequent hose testing showed that the drain box exterior was dry and the water collection rate in the wells was significantly reduced; but, still not eliminated.

Since sealing the drain box I have tried various things in search of a dry trunk. These include removing and carefully reseating the gasket in its channel in the trunk lid, sealing all the screws in the aluminum trim plate at the back of the trunk opening with butyl and adjusting the hinges and the strike plate so that the gasket is more tightly compressed when the lid is closed. All of this and after about 1/2" of rain last night I still had about 1/4" of water in the bottom of both wells. The side marker light holes and mounting screws were filled in during the resto work so leakage around the side marker lights is not the source of the water.

I have checked and at this point there does not appear to be any water entering from the front side of the trunk lid / opening. As far as I can determine the water appears to be entering somewhere around the rear corners of the trunk opening, either above the tail lights or just to the outside of the tail lights. I have done a grease smear test on the gasket and there appears to be two spots where it looks like there is a lap weld between the rear 1/4 panels and the rear panel that forms the back of the trunk. This weld seam seams to sit a little lower than the rest of the lip around the trunk and the gasket does not contact solidly across this seam on either side of the car. I don't know that this is the source of the leak; but, I thought perhaps I could bump the sheet metal up a bit with a mallet so that it is level providing for a better gasket seal; but, no deal. Whether it is the lap weld or whatever, the sheet metal at that point is very rigid and any persuasion is likely to cause distortion in adjacent panels so modification of the contact area is a no go.

Right now I am at a bit of a loss as to where exactly the water in entering. Perhaps Volvo added the drain holes because they gave up on trying to seal the trunk lid. Have any 140 owners dealt with this and found a path to a dry trunk?