Water leaking in....

isnt there a rubber grommet and wires and all going thru the firewall?...it could also be coming thru there...is it always coming in or only when you drive?

The windshield wiper insert is up about 3 inches higher then the bottom of cowl area. THere would have to be a pond of water in order to make it through those holes (and they are sealed too with a leather gasket and silicone). It would over flow the vent hole before seeping through the wiper cut out.

I was having the same issue. During my suspension upgrade, I pulled off the front fenders, and noticed a couple rot holes in the lip at the top of the fire wall, under the fender. The holes were near where the cowl drains are. I had the welder patch up the rotted holes. This could be the source of your water too maybe. Might be worth pulling the fender off to take a look.

There are three main areas to check for leaks in the front area of the car. You need to check all three areas separately and in order.

1. Check the cowl for leaks. Pour some water directly into the cowl, making sure not to get water around the windshield area. The water should drain out each side behind the front wheels. You can also look into the cowl area with a flashlight and a hand held mirror.

2. Check the windshield seal. Run some water around the windshield seal, making sure not to allow water to run over the door jambs and door glass. This is probably the greatest cause of leaks into the front of the car. A 35+ year old windshield seal is probably rotted and no longer weather tight. Also, if the windshield has been replaced or pulled recently, after market windshield gaskets are notorious for leaking - make sure to get the FORD seal if you replace the windshield seal.

3. Check the door jambs and door glass channel. Run water directly on the doors, especially allowing water to run down the glass and into the door itself. There are drain holes inside the doors that can get blocked.

Cover the floor boards with some newspaper (it will show even small drips of water very easily) and check after each test.

Tim

When testing the windshield gasket, start at the bottom and work up. If you start high, all the water will run down and if it is your windshield gasket you won't know where in the gasket it leaks. If you start low (and slow) and work up, you should be able to find it (if the gasket is the culprit).

Whats to stop rain from getting into the cowl area around where the wiper knob protrudes out of the cowl?

Blocking off the cowl vent would definately block most of the water from entering the cowl but maybe just enough is making it in through the wiper hole and then leaking through a rusted out hat.