Leak in cab

Festes

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Hi, i have a 1984 Chev C20. I have a leak coming in my cab. In the video, That’s the left drivers side dash speaker hole. Leak is running down outside wall. Anybody have an idea if it’s coming from the windshield or under the cowl (firewall joint). Thanks
 

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Rickf

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My money would be in the windshield gasket area. Remove the cowl screening and dump water in, avoiding the lower windshield.
 

Festes

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I run water in all different spots yesterday. Cowl, lower windshield, upper windshield, even over the drip edge above the door. But could not get it to leak
 

Grit dog

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Leak seems too high up to be the cowl seam.
But it’s coming from one of the only spots that were rusted out on our otherwise pristine rust free 86. The bottom corners of the A pillar, windshield frame. Under the windshield gasket. Barely visible outside the gasket, little paint bubble. Under the gasket = rust holes.
So whether it’s rusted out or not, water does get trapped there. As mine rusted from the outside- in. Not the inside out.
Just running water over it may not simulate every condition, like driving rain on the highway. Maybe hit it with a pressure washer.
Or the opposite, if you can bank on driving in some rain again soon. Tape up the windshield gasket to body and to the window. Start with the lower half/corner. And see if that blocks the water. Then do the same for the upper half/top corner. Mine was trapping water under the gasket at all 4 corners and a couple spots across the top and bottom. I actually turned 2 of the rust holes into additional drain holes rather than fixing them, on the bottom edge.
 

Rickf

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Roof lights?
 

Festes

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No roof light, I think I found where ya coming in. Top driver side windshield. Now to figure out how to fix it lol
 

CheemsK1500

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It would probably be good just to remove the windshield, fix any rust damage and get new rubber. After many years the original is super brittle and has probably developed several micro cracks.
 

Originalthor

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So I had a new windshield put in a year ago. Bloody thing leaked. Window company came up with every excuse that it was my truck. I talked to the manager and I ripped out my soaking wet carpet after a rain and showed him my rust free floor boards and said there's no way this floor pan would look like this if it has been leaking for 30 years. It's your windshield. He said he would take came of me. Well that dumb (word i can't say) took a tube of caulking and pumped it around my gasket. Then I really lost it and got my money back. Truck hasn't seen much rain since then cause I'm afraid of what could be trapped in there.

Anyways it was leaking at the top. If it's a newer windshield there not the same curve I found. Also sometimes the rubber gasket shrinks.
 

Festes

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Had new rubber and new windshield installed when truck was redone 3 years ago. Leaked and the auto glass shopped siliconed the rubber between the glass and rubber. So not sure what to do ‍♂️
 

CheemsK1500

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Had new rubber and new windshield installed when truck was redone 3 years ago. Leaked and the auto glass shopped siliconed the rubber between the glass and rubber. So not sure what to do ‍♂️

Perhaps you could get a propane torch and apply it around the edges of the glass and try to soften the silicone underneath . Or you can just use a baseball bat, a shop vac, and an abrasive rotary tool to achieve a messy but fresh restart.
 

Festes

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Lol. Messy expensive fresh start
 

SirRobyn0

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No roof light, I think I found where ya coming in. Top driver side windshield. Now to figure out how to fix it lol
Well you can test that if you have compressed air. Get some soapy water on the area you think it's leaking at, and from the inside blow air from air blower about 6" from the seal. If it bubbles there is your leak.

As to what to do if it's leaking there is a problem. The windshield should be pulled any rust damage to the channel repaired. Reinstall the windshield and should be fixed.

Never ever use silicone on a windshield seal. All that will serve to do in the long run is damage the paint and cause rust. I'm going to assume the windshield company used windshield urethane, not silicone. And you can buy tubes of windshield urethane at an autoparts store and kind of peal up the edge of the windshield seal and squirt some in there. If it works it'll be temporary. If your keeping the truck fix it right, or you'll likely have a bigger mess down the road.
 

Festes

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Ya. They used silicone but between the rubber and the glass. I’ll try the air trick. Thanks
 

SirRobyn0

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Ya. They used silicone but between the rubber and the glass. I’ll try the air trick. Thanks
Oh gotcha. Seems like a weird thing to do to me, but I'm not a glass guy. I do have a friend that is. My understanding is the rubber to glass part of the seal doesn't typically leak. Perhaps your seal was shot an that was their work around. It's to bad you don't live in the this area he'd fix you up. Let us know what you find with the air trick. Just be careful not to get it to close to the windshield or you could make a good seal leak. Hold the nozzle about 6" away is what I was taught. If you happen to have Sprayway glass cleaner on hand it works great for this and is easy to use, but anything soapy is fine to.
 

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