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Pontiac Grand Prix Water Leak



  • Trunk Leaks seal has no cracks or tears.
    Taken to several dealer and they can not figure out why I have water standing in my truck. Any suggestions.
  • I have a 2005 Grand Prix and my floorboards passenger front and rear were soaked with rain water. It took my 2 1/2 hours to vac all the water. Just this morning I took it to the dealer. He told me the cowl was leaking soaking the floor and the trunk . He also said it would coast 310.00 to fix it. Iam pisst because I bought an extended warranty and they said it wont cover the leak. So I asked why did I buy this warranty . They said to cover the car but it wint cover the leak. I hate car dealers.So now it is being fixed for 310.00
  • That is awful! They KNOW it's a design flaw. It's been happening since the 90's! Mine is a 2000. I had to have my windshield replaced due to a crack and I'm hoping that since I told them and asked them to that they added silicone or something to keep the seal.
  • gtprixgtprix Posts: 1
    I had a similar problem, it was the tail fin silicone around the bolts. There are six nuts attaching the fin to the trunk lid (bolts are embedded in fin). The silicone around the bolts had deteriated and was allowing water in. I cleaned up the area, apply a health layer of black silicone and no more leak. Hope that helps. :shades:

    My problem with leaks is when I run the AC. I it hasn't rained in days and yesterday I was blasting the AC on a long ride and water starting pouring out of the passenger side floor vents after an hour of running it. It has to be the AC somehow I'm just not familiar enough with where the water run off from the AC is at.
  • henriejohenriejo Posts: 2
    I have a major water leak in my 2004 grand prix. It first happened around 2005 when it rained during hurricane Katrina. I didn't really think anything of it. Thought maybe the water in the backseat could have wasted because we had water in the cooler for our road trip when we were getting out of town.
    Well, we moved to Oklahoma, and for this year it has been very rainy and stormy. Water has been getting in the car nonstop. I finally decided I had enough when water was stagnant on the passenger rear floor board and took it to the shop (pontiac dealership)last week. My insurance covered it because they said it could be water damaged.
    So the car sat up there 10 days. No solution. No problem. No one knew what was wrong. The insurance decided to replace the carpet that was molded by the rains without knowing what was wrong. At this point, I became really upset. Covering up the problem without fixing it. I also forgot to mention that water had gotten into the car 2 months prior during a heavy rain and knocked the a/c out. The a/c was fully functioning fine until that night. Well, the insurance decided it was not the water that knocked it out, it was a mechanical issue and my warranty covered it. So back to the story. I called the insurance and went off on them asking them how can give an estimate, release the car and try to cover up the problem without knowing the cause. This was 2 days before I picked up my car. They said they needed to see if they could find out what the problem was first before they could do anything else.
    I decided when Thursday rolled around, I would just pick it up. It better be dry and if it happened again, insurance was going to pay. I was going to find someone that could diagnose the problem. There was still no resolution to this ongoing issue. Thusday was accompanied by a heavy rain. Friday rolls around. I am at work at 6:00 PM. Mind you it is sunny, and nice. I haven't felt the carpet since the rain, so I decided to. Front driver side. Dry. Front passenger side. Dry. Back driver side. Dry. Back passenger side. Wet. Wait a minute? Wet....So the water has something to do with something near rear passenger that is causing water to build up in the car. I called the insurance back upset. I told them that water is coming in the car still, and they need to fix this problem. They are obviously missing something. Well, the guy who handles my claims is off. Great. He won't be in until Monday. I told them well, I need this fixed now. I was advised I can take my car to a shop and be reimbursed for any out of pocket expenses. So I will take the car in immediately as soon as a shop opens while this is fresh. I also started researching on the internet to see if there are people that have this problem and low and behold....A lot of people seem to be having a problem with leaks. I was really surprised because it was a shot in the dark. I just want to know if anyone knows what is causing the water to first enter the rear passenger side? What could be causing this issue where water is getting into my car? :cry:
  • nategreynategrey Posts: 2
    I have a 1998 pontiac grand prix gtp coupe and my passenger side floor gets flooded everytime it rains.

    Temporary solutions seem to be that when I park the car DOWNHILL, water doesn't seem to get into the passenger side floor. When parking straight or even uphill, that's when the water starts coming in.

    I'm going to try some of the suggestions on this forum to see if I can fix it completely.
  • henriejohenriejo Posts: 2
    The body shop finally found out what was wrong with the car. They said the seal on the windshield was bumpy and was letting water in. They also said there was a loose cowl, which was diverting water into the car. It was a good soaking rain the day after I picked it up, and I checked the car. No leaks. Clean as a whistle. I am very happy this was finally solved. They had the car for almost two weeks trying to figure out what was wrong with it. I was so worried it would not be solved. I would suggest looking to see if there is a problem with the cowl which probably has something to do with the majority of all grand prix leaks. I saw there was a recall about it on pontiac website. Also try looking at the windshield to make sure it is sealed all the way. These problems could be an issue since your leak is coming in the same side mine was.
  • My 2000 gran prix has been leaking water in the front passenger side also, i fixed the rubber seal as stated in another post and this solved the rain problem but now the air conditioner is leaking into the same area just as bad as when it rains, i know its the a/c because it leaked on a sunny hot day with no rain, i read of a fix on an a/c drain line in another message, does someone know the exact way to unplug the line? any help is greatly appreciated.
  • This worked for me but I would add. You might want to go to Auto Zone and buy some 5/16" nylon rivets, 961-060 by Dorman before you pry them out, because they are worthless after you pry them out. Also there is a another cap on my 2001 with a flat line that screws out which is reusable. It's also advisable to pry the rivets out from under the hood so you don't damage your windshield, I used a nail puller.
  • What is a COWL and where is it located?????
  • I am having the same problem. Did you ever isolate the cause of your leak on the back passenger floorboard?
  • No, I sure didn't. Even with the new windshield it happened again. I was able to find the spot where it came in, way up under the dash, you'll find an opening you can put your finger through. Why it's there I don't know.
    I actually sold my car a couple of weeks ago.
    Good Luck!
  • Hey just wanted to reply to you.
    I have not had a problem with that spot again .
    I took my car to the dealer they found a leak in the cowl .They also wanted to charge me $ 325.00 to fix it even though it was still under warranty. and still is
    I plan to traed it in this spring
    thanks fboy
  • jamijanjamijan Posts: 2
    I am also interested in unplugging the a/c drain line. Does anyone have ideas? I have a 2001 Grand Prix. The other tips have been helpful but my car is also getting wet on the front passenger side floor on warm dry days when I use my air conditioner. The blower is leaking water. Any help would be greatly appreciated. Thanks.
  • I was finally able to get this issue solve, i found the rubber strip that is under the plastic piece by the windshield and sure enough it was off so i glued it on with some rubber cement. fixed the rain problem but still had the ac condensation flowing back up because the drainage tube was clogged. couldnt find it on my own, took it to a garage that my father recommended and he put it up on the lift and showed me where it was at and stuck a small phillips screwdriver or and small thin metal object to stick up the tube and unplug it. it took like 2 seconds. it is hard to see the tube i wouldnt have found it on my own but on a lift it was easier to locate . it came down right around where the engine and tranny are, pretty much directly inline with the firewall but it was a very small tube like an 1/8 inch or something. the end of it was greenish because of the mold and gunk so it really didnt look like it could have been the tube but he stuck the screwdriver about 1 inch or so up into it and all of the water which wasnt really alot came right out and it solved the problem. you might be able to find it if you put it up on jack stands and have a little room to look around, that was my problem, i couldnt really see it from just looking underneath. but once it was on the lift it was definitely findable. good luck. i believe this will solve your problem.
  • jamijanjamijan Posts: 2
    Thanks bigskidogg. I found the drain on plugged it and the problem is sloved. I found the drain looking in from the top. In my 2001 Grand Prix under the dash on the passenger side, I had removed the cover over the blower, held in place by three anchors. I followed the pipe coming out of the blower into the firewall. Then I looked under the hood where this pipe should come out. There was the drain. a short elbow coming out and pointing down. It was difficult to reach but I was able to unplug it with a piece of stiff wire. My car has been dry since then. Thanks.
  • taylor981taylor981 Posts: 1
    I have an 04 Grand Prix and lately I have noticed that whenever I get home from work or a drive anywhere, there is a nice puddle of water underneath the car where the A/C would normally drain out, except I haven't used the A/C. I've actually had the heater on. The puddle keeps getting bigger and bigger each time. This morning when I started the car and left for work, there was already a puddle of water in the driveway after the car running for only maybe 5 minutes. I popped the hood last night and found the water was coming out of a drain elbow that looks like it's going into the firewall. Why is my car leaking so much water on the ground???? I've never had this happen with any other car I've owned.
  • jlgiffordjlgifford Posts: 1
    It doesn't get any better in 2006, my back passenger side foot well is a nice puddle and my car stinks like mold. Living in Florida, I can rest assured there is mold all over the car and it is now a health hazard. I would like to know why, if this has been an ongoing problem, hasn't GM done anything about it?
  • nategreynategrey Posts: 2
    GM doesn't do anything about it because people are still buying it.
    Seems like lack of dilligence on their end as a means of cost saving. They're actually saving at the cost of their customers.
  • I have a 2004 Grand Prix and, like all of you, my passenger side floors and air conditioner have water leaking problems. My car also smells like mold and has since i bought it. When i speed up or go over a speed bump I can hear water sloshing around in engine/dashboard. The air-conditioned air smells terrible. I got my windshield fixed over a year ago and since then, the water leak on the floor has been minimal, but the air conditioner problem is bad. I'm taking it to the dealer tomorrow after reading this thread
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