Cowl area water leak

I have a 1990 XJ which has an elusive water leak in the cowl area. It causes water to leak into the passenger side floor. The windshield has been replaced and thoroughly checked to be absolutely sure that it is not the source of the leak. The fan box has likewise been eliminated as the culprit. This leaves the cowl. When water is poured on the cowl area, it eventually shows up in the floorboard. I currently have the carpeting removed, and the front fenders off the vehicle. There is a pinch weld where the cowl and the inner fender are joined at the top. This pinch weld is covered with seam sealer from the factory, but it has dried out over time. I intend to remove the old sealer and apply it fresh. The location of this seam is just below where the antenna comes up through the fender. The top of the cowl on the right side of the vehicle is a solid piece of metal (no access to the cowl innards from the top). Does anyone know if the seam I refer to is the likely source of the leak? I am tempted to cut an access hole in the top cowl metal to gain access to it's interior but that would be useless if there are no sealable seams in there. Also, is it it a good idea to use spray undercoating/rustproofing chemical through a long wand to coat the inside of the cowl? Any advice appreciated. Sorry for the long post. Thanks in advance.

We have a '95 that had a similar leak. What I did was to run some water into the cowl vent near the left wiper and watch where it trickled down the inner fender on the right, and flow along a seam just below the blower motor. The sealant on the seam was dried out, and it allowed the leak to appear sa if it were coming in the heater.I had removed the blower so it was easier to see the seam. I used some construction adhesive to caulk the seam, and the car has been leak free since. I hope this will give you a place to look, as the ugly goop smeared around the windshield on this car shows that someone suspected the windshield seam, but was mistaken.

Sounds great HAYHAR I have a similar problem in my 88. I thought it was the lack of a grommet on the radio antena hole in the kickpanel but I siliconed one in and it still leaks. I bet it's the seam you described.

Thanks,
RBB

well i have a crack in my heater box and water drips out of it when its rainng and the hvac is in the off position, where would this be coming from?

well folks....this is just one of those XJ things. I and several friends have or had the same prob. After tearing out the dash and what seemed like half of the front end........we discovered that it leaks at the blower system intake under the passenger cowling.
Ours only leak noticably when the front of the vehicles are on an incline. so....park it facing down hill until you have time to remove the fake cowling cover..dremel out the access hole on the passenger side...seal around the intake..and patch it back...LOT'S OF Fun but I still luv my XJ!
Keep the durty side down!