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Solutions for water leaking from dash

hawkeyestoob

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I get a significant amount of water leaking from under the dash on my 67 Belvedere II when I wash it or drive in the rain. This is a non AC car and it happens if the floor vents are closed as well. I have searched the forum and did not see anything that seemed to cover this. Is there something I should be looking at or can do to address this, or is this just one of the quirks I need to be ready for and keep my fan handy for drying it out when in the garage.
 
Check your wiper pivots. I spotted some drips that way after suspecting my windshield seal (and then still having the problem after pulling the trim and attempting to re-seal it). I had replaced mine quite awhile ago but they had dried out again in Oregon sun. If you lay on the floor, you can see the passenger side one looking straight up.

I bought the kit from Dante's that includes the grease fittings, make sure you add them as they will help - when I started pumping grease in, I forced a decent amount of water out from inside of the pivots!

Using a gallon pitcher and dumping water progressively higher on one side of the car can help nail down the leak. Start by trying to flood the cowl to check the drains, then around the pivots (wipers running can help find intermittent/tricky leaks here), then up around the windshield frame.

There are a number of "flowable" silicone products that can help reseal your windshield gasket if you find trouble there. I also have a bit of rust in one corner but I am too wary of cracking the thing and not being able to find replacement glass or seals.
 
Check your wiper pivots. I spotted some drips that way after suspecting my windshield seal (and then still having the problem after pulling the trim and attempting to re-seal it). I had replaced mine quite awhile ago but they had dried out again in Oregon sun. If you lay on the floor, you can see the passenger side one looking straight up.

I bought the kit from Dante's that includes the grease fittings, make sure you add them as they will help - when I started pumping grease in, I forced a decent amount of water out from inside of the pivots!

Using a gallon pitcher and dumping water progressively higher on one side of the car can help nail down the leak. Start by trying to flood the cowl to check the drains, then around the pivots (wipers running can help find intermittent/tricky leaks here), then up around the windshield frame.

There are a number of "flowable" silicone products that can help reseal your windshield gasket if you find trouble there. I also have a bit of rust in one corner but I am too wary of cracking the thing and not being able to find replacement glass or seals.
Thanks for the detailed explanation of what you did on your car. I will start by looking at my wiper pivots. I am sure my wife will be happy to dump water on me as I am looking up from below!
 
Rust in the cowl
Yes .....remove the drivers-side vent box and put your hand up to feel around the rubber seal on the cowl.....could be either rust or build-up of leaves or tree droppings.

Or just take a good look at the firewall from inside and look for water staining.
 
For me, it was the failure of the old windshield weatherstrip. I did the wiper seal pivots first, and then it was evident that that wasn’t the problem. (Also, I think the windshield wiper pivot seals sold nowadays is cheap garbage anyway).

When I went to replace the windshield weatherstrip, I took my time and did the job in a way I thought was right. Put a good, continuous bead of sealant between the weatherstrip and the metal body, as I’ve seen on some YouTube tutorials.

But, I placed no sealant between the glass and the weatherstrip. When I first put on the windshield and tested it with a hose, everything was sealed nicely, but a year later when I washed the car, it was dripping slightly. And it was obvious that the water was wicking between the glass and the rubber. So at some point in the future, I will have to revisit this -frustrating to say the least.

Good luck with yours.
 
You could try spraying water into the cowl vent from outside of the car but keep it off the windshield and wiper pivots. If it leaks you probably have rust holes in the cowl if it doesn't leak through the inside of the floor vents. Or do the same to the windshield and pivots but keep water out of the cowl vent.
 
You could try spraying water into the cowl vent from outside of the car but keep it off the windshield and wiper pivots. If it leaks you probably have rust holes in the cowl if it doesn't leak through the inside of the floor vents. Or do the same to the windshield and pivots but keep water out of the cowl vent.
That's a really good idea and something I can easily do in the warm of the garage.
 
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For me, it was the failure of the old windshield weatherstrip. I did the wiper seal pivots first, and then it was evident that that wasn’t the problem. (Also, I think the windshield wiper pivot seals sold nowadays is cheap garbage anyway).

When I went to replace the windshield weatherstrip, I took my time and did the job in a way I thought was right. Put a good, continuous bead of sealant between the weatherstrip and the metal body, as I’ve seen on some YouTube tutorials.

But, I placed no sealant between the glass and the weatherstrip. When I first put on the windshield and tested it with a hose, everything was sealed nicely, but a year later when I washed the car, it was dripping slightly. And it was obvious that the water was wicking between the glass and the rubber. So at some point in the future, I will have to revisit this -frustrating to say the least.

Good luck with yours.
I very easily could be a combination of factors at play here.
 
One trick I have used is close the car up tight and turn the fan on high to pressurize the cabin. Then use a thick soapy mixture and look for bubbles.
 
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