Rain Water Leaks into Cab

[Seventy Two]

Hi,

I am newbie to the site.

I sure could use some helpful tips on finding out how the rain water is getting into the cab of my 72. After a rain I notice water has run down the kick panels and onto the floor. Anybody know how to resolve this?

Thanks!

[basemodel67]

Either leaking in around windshield or leaking through the kick panel vents. Try to follow the drip up to see where it starts... these things are about as water tight as a cheese-grater.

BTW - Welcome to the board!

[cdowns]

if sealant in the driprails is dried out rainwater goes into the roof and leaks down (a major cause for roofrot)

freash air intake on the cowl flap gasket not sealing is another common leak

winshield wiper mounts can leak

[69sixpackbee]

also..., the corners of the cowls. When the sealant starts to degrade and fall apart you get leaks when the water pools in the cowl.

[GruntMoanCough]

Also, check that the drains (behind the backs of the fenders) for the cowl are not plugged up with leaves, debris, etc.

BTW, Welcome!

[GASoline71]

Originally Posted by basemodel67

these things are about as water tight as a cheese-grater.

HAHA! That's a fact.

If I get caught in the rain driving my '72 GMC... my feet get wet...

Gary

[ChevLoRay]

Wanna see some pix of what happens if you use the wrong sealer to stop the leaks? Use an automotive-grade silicone sealer....not an industrial grade. But, here's some pix of how bad it can get....with the wrong sealer.
The first pic is where the wiper motor mounts....or used to be until it fell out one morning on my way to work....in the rain.
The second pic is where the HVAC motor/evaporator housing used to be mounted. Notice that the drip rail on the firewall is also trashed. The previous owner thought he was doing the right thing by daubing liberal amounts of sealer on the rail, around the housing and created a dam between the motor and housing that caused water to pool above them.
The third pic is not my cab, but shows where the outside of the kick panel is and where the crap accumulates and causes rust.

[Shane]

if I were a betting man my money would be on the windshield rubber/gasket ...

[Seventy Two]

Wow!!

Thanks everyone for the input/suggestions. I will check into this right away and see what I come up with. I would like to get it sorted out before I pull the cab from the frame and mount it (cab) on the rotisserie.

Thanks Again!

[swamp rat]

Originally Posted by cdowns

if sealant in the driprails is dried out rainwater goes into the roof and leaks down (a major cause for roofrot)

freash air intake on the cowl flap gasket not sealing is another common leak

winshield wiper mounts can leak

>>>freash air intake on the cowl flap gasket not sealing<<

Say what?? whats a flap gasket?? LOL!

[swamp rat]

Originally Posted by GruntMoanCough

Also, check that the drains (behind the backs of the fenders) for the cowl are not plugged up with leaves, debris, etc.

BTW, Welcome!

There's drains?? Learn something new every day!

[Palf70Step]

Don't forget to check where the radio antenna wire enters through the cab. The goop put around the wire to seal it will dry out and leak also.

[msgross]

cowl area is my guess...

The entire deck over your fuse box can rust out, junk in the vent area will clog those drains too...

[ChevLoRay]

I guess the best way to insure the cowl drains "efficiently" is to add a 2-inch hole to the bottom of the vent area, so whatever falls into it, falls out. If you add some screening to the bottom of the cowl louvers, that'll help keep the riffraff out, too. Then, it shouldn't be anything but water that has to drain.

[yukon ratrod]

welcome to the site! nice to see someone a little closer to Whitehorse! well some what closer anyways. feel free to question us up, thats what we are here for.welcome aboard.

[Seventy Two]

Thanks Yukon. Your truck is sweet. I enjoy watching the progress and it provides inspiration for mine. I've got the cab on the rotisserie. I'm still dealing with rust repair.

[RenoKeene]

Mine had a bit of a problem at the top windshield corners.
And welcome to this place!

[oldgold70c10]

Originally Posted by ChevLoRay

I guess the best way to insure the cowl drains "efficiently" is to add a 2-inch hole to the bottom of the vent area, so whatever falls into it, falls out. If you add some screening to the bottom of the cowl louvers, that'll help keep the riffraff out, too. Then, it shouldn't be anything but water that has to drain.

x2 on that. I hot glued window screen to the underside of my cowl grille after I cleaned it and sealed the leaky seams at either end. Anything small enough to get through the screen will go out the drain holes under the kick vents, and it keeps the leaves, bugs, and rodents out!

[mpotts64]

I have a 68 cab that does the same, I am replacing it with a 67 small back glass cab. Look under the dash on both sides and you will see a seam above the fuse block on the drive side and above the heater box on the right side. If you look closely and follow that seam all the way up you will see it goes to the windshield. If you pull the cowl you can see that seam at the windshield and look in under the cowl and make sure that seam is not rusted. What happens many times is it will rust at the windshield and then run down inside the cab along that seam and rust out that seam. Be sure to check both sides. Like was mentioned earlier, check the hole for the wiper motor and antenna cable. You cannot see the seam with the cowl on it, you have to pull the cowl. Check that very closely. Also, check the firewall where that wiring harness lays. Pull that wiring harness and take a screwdriver and go along that edge to check for rust. As for me, if they are rusted there along the seams under the cowl, get another cab. Pull the cowl and then take a water hose and run water onto the windshield, get a flashlight and look under the dash to see where it comes in, best of luck

['72_Cheyenne_Super10]

Originally Posted by Palf70Step

Don't forget to check where the radio antenna wire enters through the cab. The goop put around the wire to seal it will dry out and leak also.

Yep... I just took my cowl off searching for the leak source and sure enough, nothing was arouund the approximately 1/2 in. hole for the antenna wire! I plugged it with silicone and so much for all that rainwater in my passenger side floorboard.

[SEA-HAWKS]

I am having similar issues with my 71 C10. I am at a loss. The water is not coming from the window because I had it sealed twice, once wasn't enough. The water is coming from the cowl somewhere. While driving in the rain my left foot gets wet with all the water that drips down and is ruining my carpet padding and carpet, my truck is to nice to have this continue. Does anyone have an idea on where the water is coming from. Thanks

[nitroscott]

Im having a problem with getting rain and leaves thru the air intake under my cowl. I removed the plastic flapper on both my 72 and my 83 because they were both broke. Can I block off those intakes and still get air to my blower fan? I asked the question on FB 67-72 and know one has a clue what I am even talking about. Is the Facebook the page run by the same people as this site that I like much better? Thanks

[Sammy]

Water hose method providing a constant stream while laying in the floor with a flashlight should point you in the right direction.

[Elliot949]

My truck was doing that and we found that GM screwed up the pinch weld on the left top of the firewall... we went in just recently when we media blasted the cab and got the old "seam sealer" out of it where it was never really adhered to the firewall and re sealed it... My understanding this was a common problem on the 67-72 trucks...

[nitroscott]

Thanks for your response. My water and air is coming from the outside air intake hole under the cowl. Has anyone covered that hole and did that eliminate the problem?