i was helping my friend work on his 84 trans am and we noticed both driver and passanger floor has water under the carpet and u can see a stain were it is comming from. i made a quick drawing so u no just what i mean but both passanger and driverside had the same stain trail in the same spot.. i am thinking is has something to do with those vents were the wipers are?? and i am guessing those vent are there to get rid of water right??? and somehow leaking into car. how do we fix this problem its just killing the carpets and cant be good for the floor boards.

Passenger side could be from the fender hole (don't know the technical term). Your wiring harness goes through it to plug into the ecm, it may be lose, only hole I can think of that would put water in from the rocker panel on the passenger side, drivers side im not too sure.

Could it be the heater core?

Well heater core is usually antifreeze and youll deff. know if its that. But Im sure water could get in through a hole in the fender or maybe the door?

Nate

Had the same on my 84, it's the firewall. Up where you have the drainage just below the windshield wipers you have a cover "net" (not sure about the proper English term as I'm Swedish :-) if you remove this you will see there is some different sheetmetal meeting and seems like the water came in that way. I use a spray can of clear undercoating and filled that area and it stopped the leakage over the years it came back so I had to re do it.