Can't find the source of interior leak

Tiny
DGRIFFIN123
  • 1999 PONTIAC GRAND AM
  • 120,000 MILES

I have a 99 pontiac grand am, and the rear passenger floor is always totally soaked. I really don't see where it comes in from. There doesn't seem to be any leaks from the door at all, and from what I can see theres nowhere underneath the car that it could be coming from. Also, my driveway is on an incline if that makes any difference.

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Tuesday, January 10th, 2012 AT 8:20 PM

17 Replies

Tiny
DGRIFFIN123
  • MEMBER

Also, my trunk has water problems as well. It had several inches of water in it at one point, the spare tire was totally underwater, so I punched a small hole in the bottom of the trunk to let the water drain out.

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Tuesday, January 10th, 2012 AT 8:24 PM
Tiny
FIXITMR
  • MEMBER

Some have reported the spoiler mounts in trunk? Someone also suggested door is not draining properly and then overspilling into car.

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Tuesday, January 10th, 2012 AT 8:40 PM
Tiny
FIXITMR
  • MEMBER

And this was reported. All Pontiac grand prix from 1999-2009 that leak water on passenger floor is from the following: The front cowl panel, [Where windshield wipers are] Has a air box inside the panel, That when built has a two piece construction that is sandwiched together at factory, and over time, summer heat, Icy winters etc, dries out and allows water to get into air box and drip out below dash on passenger side. To fix: Remove wiper arms, remove cowl screen, and you will notice a box looking square on passenger side, Clean out in and around box opening top. Must be clean and dry. Next use ether urethane windshield sealant, or silicone water proof sealer. Reseal all the way around box, [Where metal body meets air box.] Make sure to re seal all the way around air box and let dry overnite. You can buy ether sealants at your local automotive parts co.

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Tuesday, January 10th, 2012 AT 8:42 PM
Tiny
DGRIFFIN123
  • MEMBER

Awesome, I'm gonna go check that out right now. Thank you for the quick reply!

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Tuesday, January 10th, 2012 AT 8:46 PM
Tiny
CADIEMAN
  • MEMBER

It comes from the front cowl area. Open the hood and look for any lose rubber gromets on the firewall. Remove the under dash panels then pull the carpet back on both sides. Which side is wet by the firewall?It leaks in and rolls back to the rear behind the front seats. Have a helper spray down the firewall. You stay inside and look for waterleaking in. These leaks maybe from a split seam also. Remove the trunk carpet then get in the trunk with a flashlight. Let your helper flood the trunk out. You should see no light coming through anywhere. Check the l and r trunk hinge area. Then check for a leak at the wheatherstrip. Youll find them keep looking. Youll need to strip out the interior to dry the carpet to get rid of that smell.

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Saturday, January 21st, 2012 AT 7:17 PM
Tiny
NICK KLEINTZ
  • MEMBER

For the trunk leak on the pass side in trunk remove carpet and you will see a flapper valve thing seal it! And for back seat floor theres a plug in the floor that probally came loose just go under car and seal that as well. Hope that helps ya!

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Wednesday, January 4th, 2017 AT 9:53 AM
Tiny
2CARPROS KEN
  • ADMIN
  • 7,021 POSTS

Hey,

Great addition to this thread! Please feel free to help out on the site whenever it can add information that will help people.

Best, Ken

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
T.H
  • 1997 PONTIAC GRAND AM
  • MERGED

Interior problem
1997 Pontiac Grand Am 4 cyl Front Wheel Drive Automatic 150000 miles

When I bought my 1997 Grand Am Gt I noticed underneath the floor mats was damp. I was told that there is a seal inbetween the window and windsheild wipers, and water seeps through there. How can I fix this leak? If that is where it is coming from.

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
BMRFIXIT
  • EXPERT
  • 19,503 POSTS
  • MERGED

If the windshield that is leaking than best to remove windshield and reseal it
glass shop is your best bet

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
IAMSICKOFMYPONTIAC
  • 1997 PONTIAC GRAND AMPONTIAC GRAND AM
  • MERGED

1997 Pontiac grand Am Grand Am GT v6 137,000 miles. Recently I have noticed that the floor underneath my driverside floor mats is wet. I had this problem about 8 months ago and I had the mnifold gasket repaired along with the heater core, but now it seems the problem has continued. I recently checked this becasue as I went to get my oil changed last week, the said my coolant was very low, so I checked the floor and it was wet, could it be the water pump? I really do not know, but I would like to have an idea of what it is so that when I go an have it looked at I know whats going on, what do you think it is and about how much will it cost? For the time being should I just keep an eye on the coolant level and keep filling it up until I can get to a mechanic? THANKS

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
MMPRINCE3000
  • MEMBER
  • MERGED

If it's coolant it is most likely the heater core, they may have done the repair incorrectly. Look at the heater core and see if it is leaking. A leaking waterpump would not leak into the cabin. Buy a Haynes manual and investigate the heater core.

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
MIKEJONES2007
  • 1996 PONTIAC GRAND AM
  • MERGED

Air Conditioning problem
1996 Pontiac Grand Am 6 cyl Two Wheel Drive Automatic

when I turn on the air conditioning, it leaks in the car. Its making my floor wet, and its starting to make the floor smell. It also leaks when it rains inside my car.

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
MERLIN2021
  • EXPERT
  • 17,549 POSTS
  • MERGED

Look under the hood, on the passenger side firewall, find the evaporator case, on the bottom of it there is a drain tube, these can block up with gunk. Use a can of compressed air like a computer duster and give it a few blasts, if this doesn't work, use a piece of wire to clear it.
You will need to peel the rug back remove the plug in the floor, and squeeze as much water as you can out of the rug, then get a fan and dry out the rest. Clean out the leaves and debris in the air intake under the black cowl, to remove that remove the wiper arms and the small clips along the edge of the cowl.

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
MSROBINSON419
  • 1997 PONTIAC GRAND AM
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • MERGED

My carpet in my car keeps getting wet, I try and dry it but the next day it is soaking wet again. Both front and back carpets.

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
PAULIE6
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  • MERGED

Are you having to put coolant in it could be heater core it under dash and if leaking it would soak your floor on passenger side

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
FIXITMR
  • MEMBER
  • MERGED

That's a big leak? What was it?

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Monday, January 9th, 2017 AT 12:24 PM
Tiny
LUCKYLUC
  • MEMBER
  • MERGED

I found the solution to my 94 grand am, with wet carpets and blower freezing up in winter.

The water is coming in by the blower because the drain holes are plugged with leaves. There are 2 drain holes under the plastic grill under the windshield. The problem one is under the ventilator on the passenger side.

The hole to the right of the ventilator is deceiving; it actually goes under the plastic box and goes deep. When the leaves plug the hole, water rises beyond the blower and goes down the vent to the carpet.

I remove the plastic grill, then the hood. 3 screws hold down the plastic vent box. Then I use a vacuum cleaner to suck up the debris.

Check it with water it must come out into the engine compartment.

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Monday, January 9th, 2017 AT 12:24 PM

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