84 C10 Water Leak

[melks]

I recently noticed my passenger floor area was constantly getting wet inside the cab and have been trying to pin point the problem. I have removed the carpet and cowl and have been doing water tests but still can't seem to figure out why it is leaking. Driver side appears the same and I have no issues with water leaks...Anyone run into a similar issue?

[kody1234]

mine was doing same thing.i was replacing the dash when I found the leak,truck sit outside all the time,was leaking around windshield gasket.hope this will help.

[melks]

I thought about the windshield gasket being the cause, but when i pour water ontop of the cowl (under the windshield) it seems to make its way down into the cab

[tucsonjwt]

You have the same problem I have had on all 3 of my squares - and I live in the desert.

Search back a few days and you will see a thread discussing this kind of leak. One suggestion is to check to see if the drains from the cowl down to the bottom of the fenders are clear.

Also, there is caulking in the cowl that degrades and allows water into the cab.
You need to remove the wiper arms and cowl screen/grille to check this out.

I bought new rubber hood hinge deflectors (the rubber pads around the hood hinges) from LMC but they are not worth buying (IMO) - too thin and very cheaply made - so I wouldn't bother with replacing them.

[Matt Man]

Check and make sure you don't have any windshield channel rust...this was one of the places mine was leaking from when I bought my truck. What a nasty surprise this was. It looks like you have some rust in the same spot mine was in.



Also make sure your kick panels are sealed nice and tight.

[gmachinz]

Another thing or two to check is the windlace seal between the fender and door-the screws that secure it usually creates rusted out holes that let water in. Also, besides the actual AC firewall box enclosure leaking, the foam seal behind the firewall box that goes over both heater core tubes shrinks and degrades over time-as water travels down and collects right below the heater core area and it let's water drain right in.

[RandyS8229]

I've been chasing the same problem. I think mine is my windshield seal. Cowl is cleaned and firewall all sealed cept the heater core. But when it rains there is no evidence of water on my firewall. Just have to keep eliminating till you find it.

[melks]

I thought it could have been the windshield seal, but when I put a hose below the windshield rubber and let the water run into the cowl area, it begins to leak into the cab.

[Matt Man]

Check your kick panel fresh air vent, the seals can go bad, mine had nothing left.

[melks]

Here is the current kick panel for the passenger side. Rubber gasket doesn't seem too bad. I notice that it folds over in 2 different directions when closed. Not sure if that is proper or not.

However the water seems to run down along the factory seam sealer on the outer most edge of the passenger floor down into the passenger door weather stripping rail.

[melks]

However judging by the rust accumulating under the kick panel air vent hole you would think that there is some water getting through the gasket and running down to the floor. Perhaps the gasket flap piece needs to be replaced.

[gmachinz]

Did you check your floor to firewall seam? GM only pinchwelded it about every 2 inches and although it is a type of flanged lip, once the spot welds start to rust, that seam will start to open up, letting water in....bad GM design but hey, these were trucks rigjt!? Lol

[melks]

Is the floor to firewall seam accessible from the interior without having to disassemble the dash/vents/insulation?

[gmachinz]

Yes....you need to pull the carpet and jute backing back from the floor just below the AC box behind the glovebox area. About an inch below where the enclosure bolts thru the firewall you can tell if water is getting in because the tops of your jute backing/carpet will be damp/wet and if its that bad, the seam may be a little scaly.

Now, if you find it is indeed wet or rusty, the only right way to fix it is to pull the entire AC enclosure out, pull the carpet out and do a full inspection of the seam....it requires quite a bit of work but this way upon reassembly you be able to gain access to seal up every area that is susceptible to water damage.

[melks]

So with the carpet fully removed I can see up by the vent box that the factory jute or insulation on the inside of the firewall is all damp. The floor to firewall factory seam must be an inch or so up from here. It looks like I will have to take apart the interior and fix this issue properly.
I figure once I have the seam exposed I will wire brush it down as best I can and use seam sealer to seal everything up. Anyone dealt with this issue have any tips or tricks?

[georgieb51]

I realize this thread left off 7 months ago but right when it looked like we were going to see photos of the actual solution the thread stopped. I appreciate all the photos and diligence of melks to work on this problem. I too have this problem and have the carpet stripped out so I can see the soaking wet insulation under the carpet. Where do we go from there? Did you solve your problem melks? Thanks.

[Dead Parrot]

Mine looked similar to the 3rd pic in the first post, except with extra rust. I had the full width rubber floor mat at the time. The padding under the mat was damp across the entire cab. Ditched the mat and replaced with carpet after patching and painting the rust spots. I am sure I still get some water there but since it can quickly evaporate, any damage is limited.

One of these days when I decide to replace the battery acid rusted out radiator support core and much of the front is off anyway, will do a better job of looking for and patching the actual leaks.