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Pontiac Grand Prix Water Leak

I have a '98 Grand Prix that started leaking water to the passenger floorboard during severe rainstorms. This happened about a year ago. I took it to the dealer and they checked the A/C and found nothing plugged up. At the time the molding around the windshield on the passenger was loose. However, that didn't seem to be the cause either. They thought it might be a cowl leak and told me to take it an auto body/glass place. The auto body/glass place looked at it and said it wasn't a cowl leak but that it appeared a was missing near the vents for defrosting (underneath the wipers). When a hose was run over this portion of the car water would run in on the passenger side footrest. The body shop even demonstrated this for me with the carpet pulled up. They said I should go back to the dealer and ask about this apparent missing piece. Went back to the dealer and they said nothing was supposed to be there. They even showed me a new Grand Prix to compare to.

I ended up going back to the body shop and paying $300 for them to make something to run the water another way by the vents and I haven't had a problem since. Wasn't happy, but it was raining a couple of times a week and I was tired of bailing out my car.
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Comments

  • ndclarkndclark Posts: 3
    I also have encountered the same problem with my 1998 Pontiac Grand Prix. When it rains really hard the passenger side floorboard will fill with water. I was in the car when it was raining hard and the water was draining directly under the dashboard from the top of the floorboard. Its lovely to have wet wires and im waiting for a major electrical problem soon. If anyone has an idea about what this may be from please help a guy out. I heard it could be from the heater core but Im not sure if that makes sense? Thanks!
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,415
    Sounds like the fresh air vent drains (under your windshield wipers)are clogged. These drains allow water to escape into drains that usually exit just back of the front wheels.

    If you carefully poured just a teacup of water down the vent grilles, you should see water exiting under the car. If you don't, the drains are clogged with bio-matter and the water rises and rises until it spills into the car itself behind the dash.

    MODERATOR

  • Same problem here (2000 Pontiac Grand Prix). Easy repair. There is a poorly secured waterguard under the plastic lip which loosly seals agains the length of the windshield. I found the issue, placed the waterguard back over the steel lip (which is all found under the black plastic. For good measure, I laid a bead of silacone between the plastic and winshield along the passenger side. Without the waterguard in place, water is channeled directly into the A/C air intake. That drains into the fan motor casing which eventually overflows onto the floor board. I found this out by placing a garden hose on my windshield and removing my glove compartment door. Haven't had a leak since.
  • rwarner1rwarner1 Posts: 1
    Same issue I'm currently dealing with. What are the steps for removal.
    Remove Wiper.
    Remove Plastic cover?
    Then what?
    Is the waterguard or seal visible at this point?
    Any help is appreciated. Right now I have to change cars with my wife when it rains. She can park in a parking garage at work, I can't.

    Please reply also if possible to rwarner1@columbus.rr.com
    Thanks,
    RW">link title
  • john59john59 Posts: 1
    I have a 99 Grand Prix. I had to replace my windshield over a year ago. Ever since, my floor boards on both the driver and passenger sides are soaked after a heavy rain. Could this be due to the windshield replacement? Maybe glass repairman's fault?
  • melodyjmelodyj Posts: 1
    I bought my car in Jan. 06. 1998 Grand Prix. Every time it rains my passenger side floorboard has 1-2 inches of water. No the ac drainage pipe (whatever it is) is not clogged. I had some wires short out 3 days ago and now my ac, radio and display lights will not work. My brother pulled out glove box for a look and found a box, audio amplifier that looks fried, could this be my problem causing the ac, radio and display lights not work. I need help, no one seems to know anything about this problem here. And how do I stop the Leak???!!!???
  • mostro186mostro186 Posts: 2
    Meldoy, sister! I had the same problem with my '98 GT! Thought it was a crack or leak on windshield. It was the water regulator inside the bottom of the windshield! It just needed to be set back in place. Have someone remove the plastic plate holding your windshield on (Lower). It's rubber and easy to fix. Don't pay someone to do it you can do it yourself grilfriend!! I HOPE this is your solution! I almost know it is! :) Marie
  • I have the same exact problem with my car... i poured water down the vent grills and the water came ou the bottom like its supposed to... now i jus took it to a mechanic and he said they have to take off the whole entire dashboard and do something with the water heater... i do not understand how all this water can come from a water heater? They want to charge me 325$ and id rather get a simple solution and do it myself.
  • I have a 99 Grand Prix GT and have the same problem. One day after a heavy rain I was driving and when I made a lefthand turn water started gushing from underneath the dash. I could hear it going through the a/c fan motor. The dealership said it was the a/c drain line and charged me to unstop it. Needless to say, it messed up my blower and resistor, which were easy fixes. The car also now has a musty smell. I still have my doubts if this problem is really solved. I never drive it in the rain anymore. I decided to sell it because i'm tired of worrying with it.
  • guestguest Posts: 774
    Have you had any luck finding a solution to this problem?
  • yes... a temp. one... keep my car in my garage when it rains lol.... but other than that, im still clueless
  • stan60stan60 Posts: 5
    The water is leaking between the plastic that sits on the windshield behind the wiper blades. Behind the plastic is a foam gasket that deteriorates and the water runs down into the heater fan motor and overflows onto the floor. Buy a tube of black silicone and run a bead across the plastic where it meets the windshield if you do not want to take the whole thing apart. It was a problem with my wifes car until I took it all apart to find the problem. Okay now. Stan :)
  • I tried using some old weather-stripping I had on hand,but still had some leakage.Yesterday I used some clear RTV silicone sealant adhesive,and ran it across most of the windshield area you speak of.It rained cats n dogs today,but I still have a small amount of water seeping in.I dropped the glove box,and can stick my hand out the rubber door behind there,and there was no water standing there,so now I am stumped as to where exactly it is coming in at.I will put more sealant around the edges if it ever stops raining.I just got the car for new teen driver,and seems we have had more trouble than its been worth.The leak fried the blower fan relay (i think),so now the fan only works on #5,but hate to replace it and have it get ruined too!I am worried the water will ruin the wires,radio,etc.Winter is coming and I NEED to resolve this!
    Also,how does one clear the things that run from front to back on each side of top of car? I dont know what they are called,but are tiny drain things.I think I heard someone say once that dealership maintenance people cleared theirs with a long pipe-cleaner thing,and ran it the length of the pipe.Just taking wild guesses now...........
    Any more help and advice would be appreciated.reply on here or contact me by email if anyone has any words of wisdom Thanks
  • New ,Used G.P.owner,I have a good idea what causes this,after looking at the way they did that being an contractor and not a mechanic,Under The car the a/c Drain pops out horizontily With that cheap tee down spout,If that down spout is loose or is not there,water would simply travel back onthat plastic nub{which pops out from inside{Walks up the pipe back into the car,I connected a 1/2 plastic pipe to the inside and routed the water drip to a better place , instead washing the dirt of thecarrage.
  • Hello Stan

    I hope you've had some success solving your problem. I recently purchased a 1999 Grand Prix and have not yet experienced any of the "leaking" issues that have been described by you and the others. However, I suspect there may be a similar problem with my vehicle because all of a sudden my heater motor will only operate on #5 (high). Like you, I don't want to replace anything until I know for sure what the problem is. Winter is already in full swing where I live so any help you can provide would be greatly appreciated.

    Thanks

    JD
  • brybrybrybry Posts: 25
    I followed ndclark message #5 instructions. I fixed the problem also and it is simple. Leave the wipers in the vertical position on your windshield (no need to remove it). Lift the hood. On the right side or passenger side you'll see a plastic cover with a grated vent on it, this is removed by unscrewing or prying on the plastic clips holding it down(2 of them)plainly visible. Remove your washer fluid hoses that are just clipped on and can be easily replaced. Remove the cowl and you will now see your blower motor down below. This is where the water is getting into your car. On my car the sponge water channel about 2 feet long had almost fallen off. I put a bead of silicone in the slot where the sponge slides onto the steel lip to hold it on so it won't fall off later. The bulk of the sponge seal points upward. Take note of its orientation and location before you remove it if it is still on the lip. This seal directs water to the proper drains away from the blower motor. It took me about fifteen minutes to correct. Hope this helps,good luck.
  • (2000 G.P-S.E) Just found this site...wish I woul have found it earlier.Have had tones of the same problems. As for the water leak I have a major one as well I get a swimming pool on the passangers side floor.Have had the heater motor and resister replaced 2 times.Getting bad again so I'am getting 2007 GXP next month...I still love My grand prix
  • I am glad I found you guys!!!!!!!!!!!!

    I have a 2000 GP GT with 79k on it.

    I have been experiencing all the problems regarding the water leak (for a year or so) and the problems with the blower fan/resister board/daytime running lights.

    I shared this information with my mechanic, who was working his thru the problems to this.

    He's going to finish today, with the help of this info, and hopefully be able to keep the bill down a little.

    My car has had one other "sporadic" issue. The car would occasionally stall, typically during SLOW, RIGHT turns. I'm hoping that may be ignition related as well.
  • craig32craig32 Posts: 30
    Anyone had any problems with 200 GP'S, SE models??
  • norris65norris65 Posts: 1
    Hello, my 2000 Grand Prix has had a small too. My friend has a 2002, his car had real flooding. We had replaced the resistor packs and blower motors, last fall. (Funny my original blower is back in now, dry out and a little WD40 & it was good to go)

    Note the rubber guards and seals were tight and in position, on my 2000 Grand Prix.

    Today we reattached my friends rubber guard and sealed it though. Then we vacuumed out both cars the blower motor areas, reversed the shop vac and blew the vents out.

    Replaced Cabin Air Filters, then installed home made water deflects. Air conditioner worked fine today.

    These deflectors will put and end to the leaks. ;)
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