What causes water leakage under the dash?

[Brian Lontz]

My windshield gasket is brand new. During rain or washing I get water leaking onto the glovebox cardboard structure & on underneath the drivers dash where the horn relay sits. It shorted out last time it got wet and had to replace it. Also there is a lot of rust on everything underneath the dash. So I’m thinking it leaks water quite a bit down there……Any ideas what causes this problem?

Thanks

 

[Richard Cranium]

Unless the air vent plenum is rotted out, either you've still got a leak through the windshield gasket or it from the wiper pivots.

If you're car is what's pictured in your avatar, what's the horn relay doing under the dash?

 

[Kern Dog]

It looks like a '70 model. I thought my own horn relays were also under the dash....
Regarding the leak...
Yeah, I get some leakage too despite a well sealed windshield. I still have the original wiper pivot gaskets....they're 54 years old!

 

[Brian Lontz]

Unless the air vent plenum is rotted out, either you've still got a leak through the windshield gasket or it from the wiper pivots.

If you're car is what's pictured in your avatar, what's the horn relay doing under the dash?

That’s where it goes on a 70 b body.

 

[Richard Cranium]

It's not here?

 

[Mopar Hunter]

My friends car leaked at the cowl because of the crud built up and caused rust.

 

[Kern Dog]

It's not here?

View attachment 1595682

Not on my cars.

 

[Richard Cranium]

Not on my cars.

View attachment 1595691

Hmm, I've learned something new.

 

[Mopar Hunter]

Hmm, I've learned something new.

Don’t you own a 70 charger?

 

[Mopar Hunter]

Here’s the horn relay on 70 Charger, right underneath the headlight doors relay (Circled).

 

[Richard Cranium]

Don’t you own a 70 charger?

Yes, but the wiring was a mess and I ripped it out and trashed it.

 

[Mopar Hunter]

Yes, but the wiring was a mess and I ripped it out and trashed it.

I was thinking it was when it was built, like what month made a difference

 

[Richard Cranium]

I was thinking it was when it was built, like what month made a difference

That may be, but back to the topic from the OP .... water leak. I think more info is needed, but there are four basic questions:

Is the cowl plenum rotted?
Was any sealant applied to the windshield molding clips?
How well is the windshield gasket sealed to the body?
How are the wiper pivot seals?

 

[dadsbee]

Hand someone a hose, get a flashlight and a comfy pillow...

 

[moparsaver]

^^^^^ Yes to the garden hose and pillow!

Take the seats out so you can lay flat…

 

[GetX'd]

I only had leakage one time inside under the passenger side dash area - for me it had nothing to do with windshield etc. Mine was the heater core decided to retire and that’s where the leakage came from. This was a 68 GTX.

 

[64fury74charger]

I don’t know if this helps but on my 74 Charger the drivers side leaked and puddled up on the floor. When I had a new windshield installed, there was a rust hole that was below the windshield gasket area that was causing the leak. The installer sealed it with the windshield goop and no more leaks.

My car only has the fresh air intake on the passenger side and it was not leaking and looked good. No more puddles since sealing the hole. It wasn’t very big but sure soaked things. It was hidden under all the accumulated dirt and debris and partly covered by the fender where it meets at the hood and door area.

 

[gtx6970]

Mine leaks under the windshield.
BUT Mine has only been wet once in 22 years . So I am not taking the chance of breaking the glass to fix it