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Mercury Grand Marquis Water Leaks



  • I've been checking every day for leaks after my fix and so far so good, and it did rain quite a bit this morning.
    I still have the carpet to one side to allow more time to dry since it was pretty wet before I worked on it. Hopefully it will stay that way. Thanks for the good advice.
  • Just to update, two days later it rained cats & dogs and unfortunately it leaked again. Back to square one, pulled again that plastic cover on top of the fan intake and the silicone I've applied was not that thick, so I clean everything up again and this time I've made a thick strip of plummers putty and sealed real tight. I did this just to
    see if it really stops the water. Once I'm sure I will prepare a rubber foam gasket of a template I've made from the plastic cover. So far with the hose it doesn't leak, but nothing like a good'ol Florida rain. Will keep all posted.
  • I'm starting to think that maybe the idea isn't so much to stop the leak as it is to give the water another destination like I did when I drilled that small hole in the side of the black plastic tray to the right of that weep hole. Still dry after 3 days of rain and original fix done in August. As I mentioned before my 96 E350 has a hose hooked up directly to that tray going right to the inner fender and right to the ground- you can see it run out when the van is moved.
    The whole thing looks like a case of bad design with the crown vics and GMC's-sorta like having to close the barn door after the horse is loose.
    Good luck and best wishes
  • Well I don't want to get you tired but again it rain and guess what, it leaked at the same place. So last Saturday I just couln't understand why if everything looked pretty sealed it will still sips inside thru the lowest bolt of that black plenum inside the car, so I pulled out the right front tire and moved the inner plastic fender just a bit enough for me to see another angle of that peep hole. At the same time I have my son blow air with the compressor hose just where I was seeing the water coming in, and sure thing it was around the peep hole, not in the actual plenum peep hole. So I spread a bead of silicone around and put everything back. Hopefully this time it'll do the trick but I haven't tried out yet, I will let it dry really good.
  • I never removed that black plastic tray. Once I seen it all filled with water I started looking for the drain so I never got as far as the gasket under it. I probably just got lucky by clearing that weep hole out and going no further. If yours keeps leaking I would either park the car with the front facing downhill,or drill a hole under the carpet to let the water out. Or,if all else fails, take it to the Ford stealership and let them do it. If it wasn't for this leak problem these are pretty good cars.
  • I think I 've finally got it, it rained last night and is all dry inside, so the problem was that I was looking in the wrong place all this time. I was already considering throwing a gold fish and have my own fish tank in the passenger side of my Marquis.
    Really it has been an excellent car and still is, I just didn't wanted to give up on him.
  • I'm glad you were able to figure it out.
  • Reading the thread above has helped me some but I still have a question. I have 96 Marquis that had a long history of water getting into floor. I bought the car and right away noticed water in passenger floor. I took windshield wiper off (flex arm back and pry out sliding lock underneith). I took right side cowl plastic grate cover off ( four screws). I then took screened cover dam off of intake plenum box (three bolts). I found the gasket under the screened dam for the intake plenum box was brittle and broken allowing water to pour down into the intake box. The intake box has a door half way down that allows air into the car. At the bottom of the intake box is a hole facing toward the front passenger wheel that drains water if it gets in. I poured water into the intake box to make sure that the drain was not plugged and the water ran free. I cleaned some minior leafs, tree needles and etc from the area along under the cowl. Water that goes through the plastic cowl grates must run off the side of the fire wall on the right side of the car inside the fender. I made a new gasket for the air intake screen and put everything back together. I haven't had another problem yet. However, I noticed when it is all back together that if water runs down the windshield onto the plastic cowl. The cowl is slopped towared the windshield wiper drive shaft and that water then must run through the cowl grates that are "directly over the top" of the air intake screen. Maybe I'm stupid but this doesn't look like one of "Fords better Ideas". If the drain at the bottom of the air intake plenum parially plugs for any reason just normal rain would cause a leak inside the car. I'm thinking of modifing the cowl by closing off the open grate in that area and installing a drain in the cowl to divert water to some place other than the air intake. Any thoughts??
  • Finally- after almost 3 months- I got in my 97 Crown Vic and you guessed it, Lake Okeechobee on my drivers' side floor. If any of you guys that tried to fix it themselves had any suggestions to get it right the first time .What would you do? Right now I'm leaning towards taking it all apart,putting a new gasket in there,and improving the drainage systen in there somehow. I got it in my garage right now after considerable effort and pulled the wet carpet and hung it to dry. It's 4:30 PM and I'm not gonna do anything 'til tomorrow so I'm open to suggestions 'til then.
  • I will reply to my own post. Only 1 thing changed since I cleaned out that drain hole back in August. I got that underspray-RUSTOP- done last week. After I cleared out that gooey, vaseline-like stuff out of the drains water began to run out behind the front tire like it should. Now I just have to wait for everything to dry out. While I was under that slotted cover I drilled another hole next to the one that was already there.I really thought that this was fixed back in August.I guess it just goes to show you that bad things can happen while you're trying to do good things.
  • I didn't get back earlier because I was traveling, but guess what went in to my Marquis and the lake was there too.
    I had left the carpet lifted since this all started and did not put it back together, I had it lifted off with some pieces of wood strategically placed to keep it off the floor. Well the main leak is sealed because this days are raining constantly and at one point I stayed inside the car while it was raining and saw water coming thru the side corner right at the end of the relay panel, but very slow so I'm puzzled by this new one. Like you did I 've tried the undercoating stuff but then again the water was not coming in thru there. I will wait till Saturday and try to
    check behind that fender liner to see if there is another opening that I can cover with silicone. Strange thing is
    I replace a broken electric antenna 4 month ago, maybe that had something to do with this, although I 've checked all
    wiring entrances into the cabin.
  • I have a 97 Crown Vic that is having the same problem. I have had the seats and carpet out so many times I am sick of it. I am in the process of tracking down the leak as described in the forums. Does anyone have pictures of where this stuff is? Looks like a piss poor design flaw by Ford. Oh yeah, the car has been recalled for a faulty cruise control that may cause it to catch fire. I would only be so lucky. Actually it is a nice car other that a mobile mold and mildew experiment. :
  • I found out where mine was leaking,also have seen this on other forums where this problem is mentioned. If you pour water into that black tray under the windshield you should see a steady drip down the outside drivers firewall. If you follow the drip it ends up on a rubber seal around the cable for the cruise control. My 97 crown vic had a crack in this seal. The water follows the cruise control cable into the car onto the carpet creating a flood if it rains for a long time. It took me several times pulling the carpet out until I found it. Once you find out where the water comes in you can seal the leak either by putting rtv sealent on the crack in the rubber grommet around the cruise control cable,replacing the cable grommet, or sealing the plastic tray so the water is directed to the side of the engine compartment down behind the front wheel. If you do any of the above you should stop the leak. If your windshield is leaking then all bets are off.
    Another way to find the leak is to shine a very bright light in the firewall area and look from inside fo the light with carpeting removed.
    Good luck I stopped mine.
  • Thanks for the info. My problem is on the passenger side, but I should be able to track it down like you described. I have the inner fender loose and blower motor out. A local glass place told me the screen below the 1st plastic tray leaks a lot. I bought a tube of the good urethane sealant that they use. He cautioned me about RTV unless it doesnt contain acetone. Will eat up metal... I am going out now to putty the crap out of everything that looks like it needs it. Will let you know.
  • Be careful that you don't seal something that is designed to drain the water.
  • Thanks to everyone for the advice. I believe I found the problem. Inside the inner fender well there is a little flap that covers the exit drain from the case. If you remove the flap there is a foam gasket between the firewall and the plastic ducting. As a mechanic told me, foam is like a sponge and why would you use a sponge as a seal? It will shrink and draw water eventually causing a leak. If Ford really did have a better idea they would use rubber gaskets. I guess there better idea is to rip off customers. Anyway I used the Urethane that I got from a window installer and sealed all the way around the hole, I am going to try running the car without the little flap and see if it is really needed. I don't believe so. I also used the Urethane on the screened piece just below the window tray. Ran a lot of water on it and no leak, at least not yet.
  • Just Bought 96 Grand Marquis Has 166,000 Km In a very good shape.
    I found that the pass.side floor is wet, so I thought they had cleaned the car before selling it to me and this part was still wet so I dried it by putting clothes under the mat and I would change to a dry clothe every couple of days.
    So far It's drying up, but I'm afraid It's a start leak even though it rained lightly for a whole 2 days and It's only damp a bit.

    It took a whole gallon of a premixed coolant before it stopped losing some (Level).

    Other than that I'm very much enjoying my new ride.

  • ralkaralka Posts: 72
    pull the carpet back on the right front floor and run water over the windshield. than look to see if water is coming out of the bottom of the hvac or to the side of the case, or from higher
  • I have a 97 Crown vic that leaks on both sides. I performed the seal the hell out of the fresh air intake and had no luck.

    I pulled out the carpet and loosened the sound deadner on the firewall and had the wife start running the hose. I found the leak on the drivers side was coming from the grommet on the hood release cable that passes thru the firewall. It was cracked.

    The passenger side was the grommet on the round bundle of wires that runs thru the firewall right under the heater box. The grommet is the larger one, about 1.5 - 2 inches in diameter and has a bunch of wires going thru it. It looks like it either shrunk or it wasn't spec'd right from the factory. What a pain to find. Hope this help some folks. Good luck.
  • felhetfelhet Posts: 1
    I never had a problem with my 96 until I moved to Texas and experienced the torrential rains there.

    I read the posts on this site and decided to investigate myself. I used to have PUDDLES on both driver and passenger sides in the front and back.

    I ended up removing the plastic cowl cover under the windshield and then the wiper tray which holds the wiper motor and the wiper mechanism. You have to take off the wiper arms themselves to do this.

    The wiper tray has channels for water to run and in the middle there is a plastic/rubber flap for the water to collect and drip down a "chute" down the middle of the engine bay and firewall. My wiper tray was COMPLETELY clogged with dirt and leaves at the mouth of the rubber flap. I vacuumed all the dirt out and cleaned all the little crevices and replaced the wiper tray.

    I also siliconed the heck out of the fresh air intake on the passenger side since the gasket shrunk like everyone else. And I siliconed the heck out of the cables going through the driver's side firewall.

    So far I have had NO problems. I did all this 8 months ago and we have had some hard rains since then.

    Hope this information helps. Let me know if there are any questions.
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