get some 3M seam sealer, you have to reseal the side panel were it meets the bulkhead. To get to the part you have to reseal take the side that leaks fender off. Take the cowl off and remove it. There are a couple of access holes on the inner fender wall you have to remove all the loose sealer first to get a better seal. Get like a flex piece of tube and fit it on the end of the sealer tube so you can fit it into the access holes and apply the sealer.
Check around the hood hinge and windsheild area by the fender for any sealer that looks like it needs to be resealed also, be sure to clean it off really good before putting the body sealer on or its not going to be a lasting effect or fix.