Rainwater Leak into 1978 Shortbed Cab - The 1947 - Present Chevrolet & GMC Truck Message Board Network

clockdoc · 02-25-2017, 08:03 PM

I’m about to lose it over this one! My 1978 C10 has leaked rainwater, on and off, for the year that I have owned it. When it rains, water drips into the cab in two places. The predominate place is onto the driver’s-side kick panel. However a leak of lesser magnitude seems to come from the circular air vent (maybe 2.5 in. O.D.) located over the brake pedal, in the duct which feeds the far-left dash air outlet. No water is evident on the passenger’s side.

When I first realized that I had this issue, I discovered that the lower windshield retention flange was badly rusted. I had a body shop cut out the rust and weld in new metal—installed new glass (old was cracked), and also a new gasket. Things were better for a while, but have returned to what I had originally.

A few days ago, I taped poly sheet over the windshield, leaving access to the cowl cavity open (bottom of plastic taped just below wiper shafts). Plastic was wrapped around the A-pillars and was taped inside the door cavities. It draped over the roof and continued down below the rear window. A heavy spray from a hose, directed at the windshield, and including the roof, produced no water in the cab after an hour.

I immediately removed the plastic and restarted the water. After 20 min. water was beginning to show up on the driver’s side.

Yesterday, I pulled off the rain gutters, sealed screw holes and reinstalled. Also brushed seam sealer on a suspect seam on the inside of the A-pillar.
An hour of water spray today produced considerable water in the floor on the driver’s side and a significant amount was dripping from the previously-mentioned air vent over the brake pedal. I can’t be sure, at this point, that the water is coming from inside the duct, as opposed to running down the backside of the duct and dripping off at that point.

I apologize for this lengthy post but I think I am suffering from info overload and perhaps can’t see the forest for the trees. Please offer any suggestions that you might have.

Clockdoc

02-25-2017, 08:03 PM	#1
clockdoc Registered User Join Date: Feb 2016 Location: Glen Allen, VA Posts: 67	Rainwater Leak into 1978 Shortbed Cab I’m about to lose it over this one! My 1978 C10 has leaked rainwater, on and off, for the year that I have owned it. When it rains, water drips into the cab in two places. The predominate place is onto the driver’s-side kick panel. However a leak of lesser magnitude seems to come from the circular air vent (maybe 2.5 in. O.D.) located over the brake pedal, in the duct which feeds the far-left dash air outlet. No water is evident on the passenger’s side. When I first realized that I had this issue, I discovered that the lower windshield retention flange was badly rusted. I had a body shop cut out the rust and weld in new metal—installed new glass (old was cracked), and also a new gasket. Things were better for a while, but have returned to what I had originally. A few days ago, I taped poly sheet over the windshield, leaving access to the cowl cavity open (bottom of plastic taped just below wiper shafts). Plastic was wrapped around the A-pillars and was taped inside the door cavities. It draped over the roof and continued down below the rear window. A heavy spray from a hose, directed at the windshield, and including the roof, produced no water in the cab after an hour. I immediately removed the plastic and restarted the water. After 20 min. water was beginning to show up on the driver’s side. Yesterday, I pulled off the rain gutters, sealed screw holes and reinstalled. Also brushed seam sealer on a suspect seam on the inside of the A-pillar. An hour of water spray today produced considerable water in the floor on the driver’s side and a significant amount was dripping from the previously-mentioned air vent over the brake pedal. I can’t be sure, at this point, that the water is coming from inside the duct, as opposed to running down the backside of the duct and dripping off at that point. I apologize for this lengthy post but I think I am suffering from info overload and perhaps can’t see the forest for the trees. Please offer any suggestions that you might have. Clockdoc



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