the mysterious interior rain leak

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df2x4

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df2x4 - all you're seeing there is a minor failure at the glue layer between the sheets of glass, the windshield is laminated safety glass. I wouldn't look at that as a symptom of anything else and certainly not evidence of a water leak. The windshield is glued on the back side of the edges against the body with a black urethane adhesive, it can fail, and also if the windshield was ever replaced the installer may not have done as good a job as the factory. I'd kinda, maybe, sorta suggest removing the A-pillar trim and have someone try aiming a water hose along the edges of the glass, varying pressure and position, to see if you spot any leakage inside using a bright light. Only reason I'm hesitant to suggest it is that it's easy to break the trim, and it may not net you a positive result anyway. :/

The way the air inlet inside the cowl is designed is that it is simply a raised 4-sided wall in the floor of the cowl area. That's why -most- of the crud that gets in past the cowl plastic doesn't end up inside your airbox, and pretty much all the water stays out (normally); but stuff like dust, small leaves, and pine needles get through and clog up your evaporator core fins. They blow around inside the cowl and make it over the wall. For it to actually leak water into the HVAC air intake the bottom edge of it along the cowl floor would need a rust-through spot.

Richard

Thanks for the info! Well I'm kind of at a loss then... I'll have my mechanic look at it next time it goes in for something and see what he says. I have a feeling it may still be the windshield though. I've heard it make some weird little creaks and groans in super hot weather, and it's the original glass, never been removed.
 

Cokeman95

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88gmctruck posted these on one of the Facebook groups about his water leaks. Don't know if you've already seen his pictures or not.
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someotherguy

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Beat me to it; I was trying to reply earlier yesterday but the site kept crapping out.

The areas you need to look at for the seam sealer, many are underneath the cowl plastic so you should remove that and inspect all of it. Do note there's a cover panel under the plastic in the same area as the infamous screw, and it's got seam sealer around it too.

Richard
 

jasons99hoe

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I know man that's my point, the mats have been discontinued so no one is making them, I cannot possibly find Dark Blue Floor mats.
have you tried stockinteriors.com. they arent very cheap but they look as OE as you can get if you really like that style. they even have an option to embroider logos. i ordered my carpet from them for my tahoe and its beautiful
 
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jasons99hoe

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Beat me to it; I was trying to reply earlier yesterday but the site kept crapping out.

The areas you need to look at for the seam sealer, many are underneath the cowl plastic so you should remove that and inspect all of it. Do note there's a cover panel under the plastic in the same area as the infamous screw, and it's got seam sealer around it too.

Richard
yall beat me to it. i was gonna say redo all the seam sealer in cowl/fender area. spot on.
 

Dariusz Salomon

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Didn't read all 6 pages but this is THE cowl screw that allows water to leak into the interior; the others are irrelevant - trust me - the others will just let water into the cowl area itself which happens constantly anyway as it normally falls through the slats in the plastic cowl piece, and goes out the cowl side drains (the plastic ducts at each end of the firewall that have rubber flaps leading into the fenders) assuming they aren't clogged up.

Except for this one screw, because it is positioned directly over the mouth of the square walled-off area inside the cowl where the air feeds into the HVAC system from outside. If this one leaks, it drips right down into the HVAC system over the fresh air flap.

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Richard
I know it's an old post but I'm just having this problem and I noticed something in your reasoning. Next to the screw you describe we see a slot that a piece of plastic cover plugs in. It's not far from the screw so I think it's also directly over the air opening and may be a potential source of leak too. Just theorising here.
 

someotherguy

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I know it's an old post but I'm just having this problem and I noticed something in your reasoning. Next to the screw you describe we see a slot that a piece of plastic cover plugs in. It's not far from the screw so I think it's also directly over the air opening and may be a potential source of leak too. Just theorising here.
I think if you pull the cowl plastic and really investigate where fresh air enters the HVAC system from the cowl, you'll understand more.

Richard
 

Dariusz Salomon

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I managed to take care of the leak today. All "someotherguy" said about the screws is correct. Mine(the screw that sits atop the HVAC) was lose so it got treatment of silicone-also I cleaned driver side drain as it seem to have been blocked. Access to drains,screws and everything connected to a subject sucks-use the ladder-I had to stand on the wheel just to get to the screws in the middle of the cowl cover( too lazy to bring the ladder lol). Now I'm just waiting for the rain-so till tomorrow.
And to all those who cared to post about their findings big thank you. Truly invaluable.
 

Keenan

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First: Thanks for the help on the string. It fixed the major water leak on the passenger side. I am attaching the picture to give a perspective of teh screw hole that drains into the fresh air inlet. this is taken from inside the truck in teh intake. you can clearly see one of the two holes that will drain directly in.

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Second: I have a trickle of water still leaking in in the corner down the weld seam. I have sealed the metal area on the cowl. (second picture) Any ideas on what to look at next?
 
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