Author Topic: Leak On Cab Floor  (Read 2109 times)

Offline Jon87V20

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Leak On Cab Floor
« on: February 06, 2022, 09:56:58 PM »
I have some kind of water leak and I’m wondering if anyone knows if there’s a place I should start looking first.

I noticed recently the edge of the front driver side floor was soaked right up near the door. However, I didn’t see any signs of where it could be from. Well today I was in there again and this time I spotted a drop or two on the panel just under the hood release handle. I didn’t have time to really investigate yet, but I shined a light up under the dashed and poked my head around. Didn’t see any thing obvious though.

Is this maybe from the windshield and it’s finding it’s way down to the floor?

Next time it’s raining I’ll try and go out and watch it too. I just really don’t want to keep filling up the floor with water.

I’ll put up a photo as soon as I can.
« Last Edit: February 06, 2022, 09:59:46 PM by Jon87V20 »
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline JohnnyPopper

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Re: Leak On Cab Floor
« Reply #1 on: February 08, 2022, 11:44:45 PM »
There are two weep holes or drains on each lower corner of the windshield. They drain to the hollow of the fender between the vent and the outer shell of the fender.

As "Rust never sleeps", it could be finding a way into the inner side of the vent wall.

You could simulate rain to see if you can see where it's coming in.

Worst case will be pulling your windshield... :(
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Geezer77GMC

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Re: Leak On Cab Floor
« Reply #2 on: February 09, 2022, 01:39:33 PM »
Leaking clearance & marker lights on the cab roof can let water into your cab.

Offline Jon87V20

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Re: Leak On Cab Floor
« Reply #3 on: February 12, 2022, 09:54:22 AM »
There are two weep holes or drains on each lower corner of the windshield. They drain to the hollow of the fender between the vent and the outer shell of the fender.

As "Rust never sleeps", it could be finding a way into the inner side of the vent wall.

You could simulate rain to see if you can see where it's coming in.

Worst case will be pulling your windshield... :(

Yeah. Well it's about ready for a windshield anyway. Maybe it's time to pull the trigger on that.
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline Jon87V20

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Re: Leak On Cab Floor
« Reply #4 on: April 16, 2022, 09:53:39 PM »
So since I posted this, I have pulled out the dash pad and looked really closely at the bottom of the windshield and there's definitely no water there. It seems like it's right at the level of this rubber plug type thing on both the driver side and passenger side on the firewall. Could it be coming in through those for some reason? I can only pull it like halfway out, then it stops and I didn't want to force it to go further. Is it okay to pull those out for inspection purposes? (see photo)

Does anyone have some kind of drawing or diagram of where water is supposed to exit from the cowl and windshield area? If these exits were blocked with pine needles and other junk, where would the water want to go to get out? I know Johnny mentioned the weep holes. However, I just think a rust problem wouldn't make it leak from both sides at once right? As far as I can tell, both sides had this happen simultaneously.

If I have time tomorrow, now that it's all taken apart, I may just lay the hose on the roof and run water down the front. I tried this last month after cleaning a bunch of crap out of the cowl and didn't see any water coming in that was obvious though.
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline JohnnyPopper

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Re: Leak On Cab Floor
« Reply #5 on: April 16, 2022, 10:51:20 PM »
Yeah Jon, I think you running water on her will tell the tale. May not be a quick task, but there should not be water where it's going.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Jon87V20

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Re: Leak On Cab Floor
« Reply #6 on: April 17, 2022, 12:35:55 PM »
Yeah Jon, I think you running water on her will tell the tale. May not be a quick task, but there should not be water where it's going.
Okay. I'll probably go out and run operation garden hose today and see what happens. Thanks!
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline Jon87V20

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Re: Leak On Cab Floor
« Reply #7 on: April 17, 2022, 02:12:03 PM »
Quick update: I let the hose run into the cowl and water came pouring out of the screw holes for the kick panel on the driver side (I have them all removed other than one that is giving me a hard time, and on the rear-most screw on the passenger side (all of the screws are still in on that one). There has to be a clog somewhere right?
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline JohnnyPopper

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Re: Leak On Cab Floor
« Reply #8 on: April 17, 2022, 02:25:22 PM »
Yes, most likely at the bottom between the fender and the body.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Jon87V20

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Re: Leak On Cab Floor
« Reply #9 on: April 17, 2022, 07:08:00 PM »
Pretty sure I figured it out. When I cleaned under the cowl before, I didn't look far enough down into the sides. There was some extremely compacted pine needles and other crap stuck in the passenger side. It was causing the water to overflow over the little wall in there and pour down into the cabin where the air vent is. The driver side is really hard to access and look into. I jammed a wire hanger down in there and blasted both sides with compressed air. When I ran the hose again, nothing came inside so I think it's good to go.
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline Mike81K10

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Re: Leak On Cab Floor
« Reply #10 on: April 17, 2022, 09:21:06 PM »
If you used a metal hanger, you can cause scratches to the finish or rust proofing. If you get bare metal as a result it can lead to rust out. A vacuum or method that does not scratch the inside finish is best.
"Tell me and I forget. Teach me and I remember. Involve me and I learn." -Benjamin Franklin

Offline Jon87V20

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Re: Leak On Cab Floor
« Reply #11 on: April 19, 2022, 07:01:22 PM »
If you used a metal hanger, you can cause scratches to the finish or rust proofing. If you get bare metal as a result it can lead to rust out. A vacuum or method that does not scratch the inside finish is best.
Oof. Yeah that sucks. I wasn't really thinking about that. I wasn't able to fit the vacuum down there far enough and I couldn't get anything in on the driver side other than the hanger because of the angle there. I should've put tape on it first or something though.
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline JohnnyPopper

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Re: Leak On Cab Floor
« Reply #12 on: April 19, 2022, 08:20:46 PM »
Sounds like you saved her bacon from a world of rusty hurt. Good job!  ;D
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Mike81K10

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Re: Leak On Cab Floor
« Reply #13 on: April 19, 2022, 09:52:47 PM »
You can use those plastic drain cleaner tools for sinks and tubs. They are fairly long plastic and might work well in cleaning out those tight areas.
"Tell me and I forget. Teach me and I remember. Involve me and I learn." -Benjamin Franklin

Online Shifty

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Re: Leak On Cab Floor
« Reply #14 on: April 20, 2022, 09:16:43 AM »
You can use those plastic drain cleaner tools for sinks and tubs. They are fairly long plastic and might work well in cleaning out those tight areas.
Nice tip!  ;)
87 V20 Standard Cab Longbed (current)

87 R30 3+3 Longbed (days of yore)

98 C2500 ext cab longbed