Mysterious Water Leak - 91 Grand AM

[84GNTTYPE]

My daily driver - a 91 Grand Am - has a leak somewhere that lets LOTS of water into the interior of my car. My car is parked in a lot all week and when I go out there during the weekend there is STANDING WATER on the floor of my car (if it rained that week). I'm talking probably a gallon each on the driver and passenger sides. The water is mainly in the front floor, but it is also wet under the seats and on the back floor.

Last weekend when I was home my Dad and I sprayed the car down with the garden hose. When we were done there was a pool around my car, but no water inside. The next day we ran it through the automatic car wash, but still no water came in.

I'd like to hang onto the car for awhile longer, but if I can't find this leak I'm going to have to get rid of it before the floorboards rust out.

Any ideas would really be appreciated.

 

[John Larkin]

I had an '87 Grand Am, first and only car I bought brand new (no money to buy a TR back then). It leaked like a sieve just as you describe but on the passenger floorboard only. Never did it with a hose, just when it rained. It was coming in from the cowl and I could never disassemble it far enough to find the leak. I removed the carpeting for the last time (after drying it out more than 3x prior) and watched for the leak. Sure enough I found a little trail of water coming down the firewall on the inside. I drilled a small hole right in the middle of the trail and built a small pocket of silicone around the hole to catch the water and run it back outside. Never had the problem again. I'm serious. Plan on replacing your padding with some Homey Depot cheap house carpet padding or you will get that stagnant pond smell. I bet I looked for that leak for 3 weeks.