Please help. Mystery Water....

I have a '93 Grand Am that I recently purchased. It had problems, and lots of them. Luckily, a friend of mine knew how to solve most of them, but he couldn't really help me figure out one thing.... one day, out of the blue, the driver's side floorboard had a huge puddle of water in it. I sopped up all the water, (using several roles of paper towels, mind you), and went about putting on my brand new high pressure power steering hose. That in itself was kinda fun. Anyhow, I got back in the car, and low and behold... the puddle had returned. No rain, and I hadn't even started the car. It was so bad to begin with that I had mold growing on the floorboard. If anyone knows what might be causing this, and how to fix it, please please please let me know. I should probably add that I've not been able to find ANY sign of where it's coming from. :confused:

Did you jack up the car to do the power steering hose ??

Sounds like the drains under the wipers could be clogged.

I didn't jack up the car, because the hose went in from the top. I really really don't know much about cars.... how would I check those drains???

Was this plain water on the floorboard, or antifreeze / water mix? If it has antifreeze mixed in, I'm thinking heater core.

I am pretty sure it's just plain water. It's clear, at least, and it doesn't have any smell to it. It hasn't even been raining when the water's been there... I'm thinking it's possessed.

Any chance this would be condensation from the air conditioner evaporator coil?

I'm thinking no on the A/C thing, because my A/C isn't hooked up. It's really messed up somehow that even my friend the mechanic couldn't fix. He can't figure out this water thing either. I'm so confused! Why didn't I just tell my dad to shove his opinion when I wanted to take auto shop in high school and he told me "no daughter of mine is going to do some man's job".......

Hhmm do you have a sunroof? Perhaps a drain is plugged

Remove the wiper arms and the black plastic cover that is under the wipers.
The drains are under this cover, one on either side, the one on the passenger side is hidden under the heaters air intake.

Is the car parked level ??

I am going to check into the wipers thing, but it's going to be a couple of hours before I can get out there to do it. Oh, and yes, the car is parked level. Also, it smells pretty dreadful in there because of the mold that had grown, so if anyone knows A) how to get the mold out, and B) how to make it smell better... please let me know. Thanks to everyone so far who has tried to help!

The underlay material under the carpet will never dry out without air movement.

I have had this problem with many cars - I always remove all the seats, console and trim pull the carpet out of the car and allow it to dry.

You can also shove some props under the carpet such as wood blocks to allow the air to circulate, but the water will generally run to the lowest part - somewhere else in the car, and you will spend just as much time chasing it.

In my experience the smell leaves when the moisture does.

WOW! I would be SO LOST trying to pull out the seats and carpet and such... would a wet vac work???

No, the carpet has a rubber backing, the underlay is under this.

The seats each have four bolts - not as big a job as it seems.

You could just remove the drivers seat, pull that side of the carpet up, poke a small hole thru the edge of the carpet, then use string or wire to tie it to the passenger arm rest or something like that in order to hold the carpet up while it dries.

that's a pretty darn good idea.....

I left this in another post on here, but it will help you. If you're going to get in there and do it, you might as well take care of everythig at the same time.

Remove the wipers and the black plastic shield to expose the damper on the passenger side. Pull it out and get a new gasket for it as the original gasket was a thin foam. The replacements are much thicker. If your old one is ok, clean everything up and put the old one back in and silicone the crap out of it, just make sure the silicone does not obstruct the damper door.

Next, while you still have the plastic cover off, check your drain holes on the passenger and driver side. The car rusts badly in both spots because of the moisture that flows down there. It will often pool if the drains become blocked with leaves, etc. On the driver side, you should remove the wiper motor as you will find there is a rust hole at the drain behind it. I went to the local Napa and bought some body seam caulk which hardens like plastic. Smear it on with rubber gloves. You may also want to caulk around both electrical blocks (the one for the computer and the one on the drivers side for the instrument cluster) They are located each side by the hood hinges. I actually used the window sealing caulk which comes in a roll that you can roll like playdough. Pack it around the blocks and it hardens in a few days and is water tight. On the interior under the dash, pull your firewall matting off the firewall. I cut mine down the center on each side to get it out and I was able to put it back in fairlly easy when I was finished. Behind the foam matting on the drivers side, look way up on the firewall above the steering column (with a light) and you will likely see where water is coming in from where the drain has rusted on the drivers side. If it is not too bad, caulk it well. It is hard to reach, but if you don't seal it, you will still get leaks. Also check the seam that runs horizontally all across the firewall. It is very prone to leaking especially on the passenger side. Next, pull back the carpet on both the drivers side and passenger side to check for rust. I found mine was starting to rust out on the passenger side. When water sprays up under the car, it is directed right against the floor board through a hole in the control arm. After a while it just washes through. I used roofing tar to seal my floor as it was not too bad, but I sealed it well. By the way, my car is in really good shape and has been rustproofed every year since new. Just bad design, caused a few leaks. Also, if you have had water coming in on the passenger side by the damper, check the electical connection that is mounted to the firewall under the glove box. Water will run right into it and cause it to corrode. In my case , it caused high idle in wet weather. I pulled the connection apart, cleaned it with WD40 and put it back together and never had the problem since. Also pull your connection out of the computer to make sure it is not green. If it is, you know water has been leaking onto your computer as well.

HOLY MOLY!!! I read that post, and immediately fowarded it to my friend that's a mechanic. I appreciate all the great suggestions! I just didn't understand some of it, so that's why I sent it to my friend.... hopefully he can get it fixed using your wonderful instruction and insight. Thank you!

Oh, my, how the mystery continues... I vaccuumed the water out of the floorboard, and ran a high pressure hose over the car to see if I could find where the water was coming in from.... anyhow, I'm afraid that I can't possibly actually do all the things listed to do, as I'm not actually automotively inclined... anyhow, as I was vaccuuming out the car, I happened to notice that the driver's side floorboard in the back was soaked.... but the area under the seat was bone dry. ...... I'm sratching my head here....

Oh, my, how the mystery continues... I vaccuumed the water out of the floorboard, and ran a high pressure hose over the car to see if I could find where the water was coming in from.... anyhow, I'm afraid that I can't possibly actually do all the things listed to do, as I'm not actually automotively inclined... anyhow, as I was vaccuuming out the car, I happened to notice that the driver's side floorboard in the back was soaked.... but the area under the seat was bone dry. ...... I'm sratching my head here....


Ha ha, now you want to talk the rear end of the vehicle. Make sure your trunk liner is sealing correctly. Check for water in the trunk that can run down the left side of the rear seat into the floor pan. I replaced the rear trunk liner with the liner off of the hatch of a 95 Grand Cherokee in the scrap yard. The liner was thicker and was enough to seal the trunk tightly...so much so that when I closed it you can hear the air pressure try to escape as it closes.

I'm glad you got a laugh out of it! You sure have done alot of work on your car. I wish I KNEW HOW to do the things you say to do. I have noticed there always seems to be condensation on the stuff in my trunk.....

As if the water problem's not enough.... what could cause the car to idle funny? It idles high then low, high then low, over and over while just sitting. I'm starting to think a scrapyard would be a nice home for this car.....

As if the water problem's not enough.... what could cause the car to idle funny? It idles high then low, high then low, over and over while just sitting. I'm starting to think a scrapyard would be a nice home for this car.....


Do a search on IAC (idle air control). Yours is likely gummed/stuck. If it is not that, I suspect TPS (throttle position sensor) or a vacuum leak. Check the IAC first.

Oh, why is it always something I know nothing about? Of course, all I really know how to do is change the oil and oil filter....
Are those things (IAC or TPS) expensive to have fixed?

Both of these information sensors are easily replaced once you know were they are - two screws and one eletrical connector each.
Fairly inexpensive as well - unless you go to the dealer.

Back to the water problem - you said the car was parked level... water will seak its own level (self level).

One day, some day you will have to lift up the carpet - when you do it should be obvious how the water could flow from the front floorboard to the rear.

You should also see that the carpet under the seat may be elevated a bit higher than the floorboard carpet - hense the dry condition here.

I keep thinking, what did I do to deserve a car with this many problems? I'm almost to the point of insanity with it, but at least today I went and got it insured. I can't get it registered or get a tag until it passes an emissions inspection, which I'm thinking at this point it won't. Dang it, I'm a mom and a model, not a mechanic. So goes life, I suppose. I'd like to be more car smart.....but for now I'll live with being a mom and having a fairly decent face! I told a friend of mine that I was going to call in a priest to exorcise the demons out of the car. Instead of saying something about how absurd it would be to perform an exorcism on a car, he simply said, "well, are you Catholic?" Geez.

Is there anywhere online I can go that will show me where the IAC and TPS are located on my car?

Is there anywhere online I can go that will show me where the IAC and TPS are located on my car?

The TPS is in front of the throttle body and is mounted by two screws. The two screws are actually difficult to remove from the location they are in so I use a pair of needle nose vice grips to grasp the head of the screw and turn. The IAC is located behind and below the throttle body and it to has two screws holding it in. Both have a plastic wire harness that plugs into them. If you are not too handy, I would suggest just have your mechanic friend install them for you. I don't usually like guessing at parts replacement, but these are relatively inexpensive sensors and not too hard to replace. In the time it would take a mechanic to diagnose the actual problem, you would be better off just to replace the sensors and see if it fixes your problem I replace my IAC every two years as regular maintenance.

thank you so much for all of your help

Turns out that, little did I know, but my mechanic friend had already replaced the IAC and TPS. So... then what on earth is causing the idling issue??? OH, and I still haven't found where the water is coming from. GOING INSANE

Turns out that, little did I know, but my mechanic friend had already replaced the IAC and TPS. So... then what on earth is causing the idling issue??? OH, and I still haven't found where the water is coming from. GOING INSANE

Was the car idling badly before the IAC was replaced? I'm wondering if you got a bad unit. You could also have a vacuum leak so check all the rubber hoses in and around the intake or listen for hissing noises in the engine compartment. One last thought, pull the kick plate and glove box out on the passenger side. On the firewall there is a bunch of wires that connect together by a black plug. Undo the plug and check the connections inside to make sure they are not corroded. If they are it would typically cause a no start or high idle, but you never know. Given the age of the car, your computer could also be failing. Mine went 10 years and started acting up last year. The circuit board gets old, brittle and can crack or if water has leaked down on the computer, the wires could be corroded there as well. I replaced mine at an aftermarket parts store as the dealer price is outrageous. They will usually give you back a credit for your old unit, just make sure you pull your eeprom out of it and put it in your new computer. Your best bet is to take it to a shop and have it diagnosed properly. Too many things could cause this and there is no point in guessing. Just check the electrical plugs first to make sure they are not corroded given that water is getting in the car.

The unfortuate part about all this is that I can't afford to take it to a shop....
I'm going to foward your post to my mechanic friend, and see if he can come next week (his next day off) and check into it. He works on diesel trucks for a living, but he's quite handy with cars as well. He's just REALLY busy. He's got a wife, 2 young kids, and he only gets one day off a week....so I don't get to talk to him often...
Thank you again for your suggestions!

i had a "93 grand am and my car did this and I was told by one of my good friends and my dad and both said it was the heating core. I am not sure what that does exactly or what work it entails to change but something to look in to.

Thanks! I will definately ask Erick ( my mechanic friend) to come by and check that out!