cndctrdj

i have two leaks in my car one in front and one in back and i can't find either one

93.FORMULA.WS6

I worked as a body tech at a pontiac dealer in dallas fort worth, and I saw several of these problems. Most of the time it would apear to come from behind the glove box. 90% of the time it ended up leaking from where the frame rail and strut tower welds to the firewall. you see gm uses a resistance welder to build the structure of the f-body. So that means that you never have a completely solid weld joining two diferent pieces of metal, you have a series of spot welds.
Gm used a seam sealer that is not flexible or self leveling. More often than not I found there to be cracks in the seam sealer at that location. So I just tried to clean the area as best I could with a razor blade and wax& grease remover before I applied my new seamsealer. I was very liberal with how much seam sealer I used, and I also used a brush to make sure I smeared it good into the cracks.
To find the leak I would first suggest taking the right front wheel off, and remove the fender liner, it should be held in with a few sheetmetal screws, (7mm) and some plastic clips. If I didn't see anything obvious at this point, I would take off the fender. Most of the time you will need to take off the fender to gain access to all of the seam sealer. I never had one of these leaks come back with the same problem.
That's just my 2 cents worth!!!

OneFlyn95z28

I am not a gm tech but have owned four 4th gens I also woprk on F/Y body's alot in the Seattle area

I have had the one in the back from broken body welds in the hatch area.

The BIGGEST leaker in the front is from the PCM pass through boot. They can crack become loose or in many cases have some thing else ran through them. I have my N20 line and battery cable going through there.

The issue is reaqlly with the Cowl plastic covering the windsheild wipers. it collects the water coming off the hood going down the road and more then you might think sittin in the drive way

WELL take a look where it drains on the passenger side......RIGHT on the PCM Pass through connector.

SO if this pass through area has been compremised at all when there is water it gets poured on and water in the floor.

I fixed the problem with a thick peice of plastic like GM used in the doors. I tucked it up under the Plastic cover and made sure when it drianed the water goes down under the A/C box. problem solved.

this fix also works for broken welds in that area but if you have broken weld I would get them fixed
Good luck!

kostya_f

First of all you should probably check on the underside of your carpet to see if it is dry. If it's wet, you will have to take it all out anyways to dry so that mildew doesn't grow and rust your floor. Once the carpet is out, finding the leak will be much easier.
Mine leaked because the car was wrecked on the driver's side and the sealant wasn't applied high enough where strut tower meets with side panel(behind fender).

Heatmaker

I had the same issue..the trim around the door had become bad and wasw seaping waterin..it trickled down into the floor just like you described...carbet was moist...papers sokcked...got a new liner..for 130.00 from GM and that was that. Da doo dom!

LT-14me

It didnt leak today and we have been raining all day So i have no idea what that was? My radiator core was bone dry also, but i think that had more to do with the fact that i didnt flush it in a while

LT-14me

Actually i take that back... It rained pretty good today and i noticed that the mat was wet again...so i traced it and i found droplets on the top of the carpet in the passenger side footwell, near the top where the lower part of the glove box meets the carpet. I traced the droplets and opend up my glove box, i looked around and i could see a reflection behind it, when i shined my flash light back there. I saw water leakein in from behind..it appears to be comeing in from behind the left hand side of the glove box near all the wires and i believe HVAC stuff. So it might be the windshield seal...i guess i am gunna have to take the glove box out and try to see exactly where it is comeing from

LT-14me

I have a rubber piece that covers the PCM pass, its more like a flap that is supposed to direct water off of it...i dont know if that is stock or not...but also my plastic tray where the water from the windshied drains is broken, it has a 3" crack in it, but i believe the water will just drain onto either the passenger exhaust manifold or down the firewall onto the motor mounts. As far as checking the welds, i have to remove not only the fender lineing but also the fender itself?

93.FORMULA.WS6

yes, you will need to take your fender off to get a better look, I doubt it is comming from the windshield seal, because the windshield is set with urathane, and on the f-body if the windshield is leaking it will only be from the top because the windshield is several inches wider than the seams of metal Underneath the windshield. There is no way water can travel up-hill. I am telling you I have had two of my own personal f-bodys that I did this to.

Jack the car up, take the wheel off, take the fender liner out, then take the fender off if you need to. But once you get the fender liner off you will see exactly what I am talking about, (GM seam sealer is brittle), and does not seem to stick very well to the car. It sounds like alot of work but is is not that bad. The Mitchel Crash estimating guide says that the fender should take 1.8 hours to remove and install. (That is with hand tools), if you have done this before, or have air tools it will be much less. Just take your time and put all hardware in zip lock bags, and try to remember where all the bolts go, and if you have a question look at the otherside. Patience is key!!! Good luck.

z28_4life

I hate to bring this ancient post back from the dead but it sounds pretty spot on with my situation. It rained hard here for three days straight and I noticed a nice puddle on the passenger side floor. I had someone run a hose on the t-top/window area, and I also paper through the window to see if it was sealing evenly. I noticed that it was leaking towards the back, down the window, and then it would run along the rubber seal at the bottom of the window. This leads to the mirror and then down into the door trim.
Here's where it gets confusing, I took the under dash piece off and noticed it was damp/wet so there's gotta be a leak up front as well? I just don't see how the water in the door panel could somehow have access to under the dash. One has to be the major contributor to the puddle on that side of the floor. I'm hoping it was just the window needing to be adjusted.