Help finding leak from rain

[chipskittles]

It's a known leak spot you have to put silicone seal on the screw holes where the cowl screws go, before you put the cowl back on. One of the holes is right over the fresh air intake so water wicks down the screw and drops right into the fresh air intake. On a related note make sure you pull back the carpet and really let it dry out for a few days. There is the felt underlayment/insulation and then there is a layer of fiberglass heat shield that will take forever to dry once it gets wet. I had to take mine out to get air on both sides of it before it would dry out enough to put back in.

 

[Bob L]

The heater a/c unit goes up through the cowl a couple inches and seals to the cowl. Water goes down into the cowl along with air, the water is supposed to go around the raised part of the heater air intake and drain over the end of the cowl behind the fender. Even if the water is draining as it should if the seal to the cowl and heater air intake is bad you will get water in. Mine showed up as water in the blower motor housing and actually pumped out onto the floor when I started the truck after raining. With the blower motor out I was able to reach up and feel the foam seal had deteriorated. Instead of removing the heater to replace the seal I just covered the other right side opening so no water comes in the rt side or the cowl at all. air still comes in on the left side and the water that comes in the left side runs out the left away from the heater. That is the prestone anti freeze jug in post #7 . I just cut the side out of the jug and stuck it to the cowl with 3-M strip caulk. It solved my leak and I am in the wetter part of the country.

 

[wheelman]

sounds like drain holes clogged.i had a water deal years back on my 96 Chevy express van
it just started one day after a rain.after a hot summer..never could find the problem.it just fixed it self..but i was worried.cause water was running down behind the fuse box.it was inside the left side kick panel..

 

[jollyjerry]

Took off the blower fan and stuffed a big towel in there. After a big rain the towel was dry, so I'm ruling that out as the leak now. Drew with chalk on the metal to see where the water was flowing and saw it run along the weld the arrows are pointing at. I didn't see anything under the hood that would be near this, and the windshield looks attached (though I'm not ruling it out, thanks chimneyman).

Think I'll open up the dash for a separate thing (evaporator), so will take a look at that later.

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[delta_p]

The gasket would seal the water from leaking around the outside of the plastic blower box unit, so i wouldn't suspect the blower area to get wet.

I wasn't sure either if the piece in the cowel was a separate piece connecting to the blower box unit and so i also silicone'd the edge lip on the inside of the box near the gasket. you can see part of gasket sticking out into the blower box but i never had the blower area wet.

There is a slight downhill in this area toward the drain hole, but if the truck sits off level the water is going to pool in this area. I only seemed to get a leak after rains where the truck sat or after washing the truck (no wiper use). And never was wet inside the blower area.

Opening up the cowel cover and after silicone the gasket, i don't have the leak anymore.

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[jollyjerry]

Great photos, I had the cowl off but didn't actually look down them. Just hosed a ton of water in and assumed that wasn't the problem. Will take off again and look more closely.

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[delta_p]

you have to remove the cover plate under the cowl cover to see that gasket. If you do remove it (not hard at all), then just silicone anyway.

 

[Fragment]

Hey I promise you I have the answer to this. Let me try and go take you a picture right now. It took me months to find this stupid leak.

 

[Fragment]

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That wiped on looking stuff is actually a flexible seam sealer. It fails in this spot notoriously. Take a razor and scrape is off around the seam I'm pointing at there, and then stuff the seam full of silicone (the black stuff in my picture). Its a little pinhole leak, but it can sure fill the truck up.

This is all I had to do to fix it. I had the entire fender and half the dash off trying to find it before I figured this out...

This is right behind the passenger hood hinge btw.

 

[jollyjerry]

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That wiped on looking stuff is actually a flexible seam sealer. It fails in this spot notoriously. Take a razor and scrape is off around the seam I'm pointing at there, and then stuff the seam full of silicone (the black stuff in my picture). Its a little pinhole leak, but it can sure fill the truck up.

This is all I had to do to fix it. I had the entire fender and half the dash off trying to find it before I figured this out...

This is right behind the passenger hood hinge btw.

Wow! No way I would've guessed that. That would match up with the symptoms of not leaking when I spray in the cowl.

Going to owe you big if that fixes it. Nice that it's already exposed so I don't have to take the cowl off again.

Rained pretty hard last night, very windy too. I have the carpet propped up so it didn't get wet again. It's draining through the hole where the kick panels mount. Been driving it around without a passenger seat. Kinda practical really.

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