Passenger footwell rain leak

[ASJT3]

Hey fellas,

93 k1500 350 has a water leak in the passenger footwell. Happens when it rains haven't had the truck long enough too test if a/c also causes leak. I checked the condensate drain line at the engine firewall. There was some gunk in it which I blew out but did not solve problem.

I'm able to reproduce leak by running a hose into the exterior cowl openings as if it were raining. As you can see in the pic the leak develops behind the blower motor. Any ideas as to how to fix this leak??

Thanks!

The picture below shows underneath the passenger dash the two locations where I've seen leakage:





The test setup:

[Schurkey]

First Guess: Blocked HVAC drain "duckbill".

Often accompanied with moldy/musty stench from heater.

[ASJT3]

Originally Posted by Schurkey

First Guess: Blocked HVAC drain "duckbill".

Often accompanied with moldy/musty stench from heater.

Duckbill? Sorry haven't heard that term before. Any idea as to how to clear the blockage?

Thanks,

Alex

[j cAT]

Originally Posted by ASJT3

Duckbill? Sorry haven't heard that term before. Any idea as to how to clear the blockage?

Thanks,

Alex

that term is used sometimes to indicate the rubber drain tube.

finding this can be a little difficult.

[ASJT3]

Originally Posted by j cAT

that term is used sometimes to indicate the rubber drain tube.

finding this can be a little difficult.

So is this a tube that runs to the bottom of the chassis?

[Schurkey]

Originally Posted by ASJT3

So is this a tube that runs to the bottom of the chassis?

Molded-rubber device about two--three inches long. A grommet on one end so it can seal the hole, "lips" on the other end so stuff (water, for example) can exit, but not enter. All molded as one piece.

It'll be on the underside of the HVAC plenum.

[ASJT3]

Originally Posted by Schurkey

Molded-rubber device about two--three inches long. A grommet on one end so it can seal the hole, "lips" on the other end so stuff (water, for example) can exit, but not enter. All molded as one piece.

It'll be on the underside of the HVAC plenum.

I'm guessing this is what you meant by the duckbill?



It was clear and not blocked. I removed it and did the same test, water still leaks in the cab.

What could this be? Am i screwed lol


Thanks,

Alex

[aleekat]

I would look for a welded seam in that cowl that normally is sealed and painted over. It may look intact, but can crack over the years and allow water to seep in. I've used some exterior 100% silicon 30yr chalk with good success.

[Schurkey]

Originally Posted by ASJT3

I'm guessing this is what you meant by the duckbill?



It was clear and not blocked. I removed it and did the same test, water still leaks in the cab.

Yep, that's it. Sorry it wasn't the problem. Can you look up inside the hole in the box that that fits into? Is the BOX full of sunflower seeds/cottonwood fluff/mouse nests, etc?

Originally Posted by aleekat

I would look for a welded seam in that cowl that normally is sealed and painted over. It may look intact, but can crack over the years and allow water to seep in. I've used some exterior 100% silicon 30yr chalk with good success.

With the drain verified, and the heater plenum not filled with debris, this is probably the next step.




For whatever difference it makes, does the truck cab stay hot in the winter and cool in the summer based on heater/AC use? My cab was cold with the heater on, and warm with the A/C running. Had a MASSIVE outside-air leak into the cab where the steel of the body transitions to the plastic of the HVAC blower housing. Foam gasket completely rotted out, and it was a hateful job to replace. The '88 service manual gives the WRONG instructions. I had to refer to the '88 service manual SUPPLEMENT for correct procedure.

[ASJT3]

Originally Posted by Schurkey

Yep, that's it. Sorry it wasn't the problem. Can you look up inside the hole in the box that that fits into? Is the BOX full of sunflower seeds/cottonwood fluff/mouse nests, etc?

I'll check, but water does flow freely out of the duckbill hole when I run the hose into the cowl.

Originally Posted by aleekat;

I would look for a welded seam in that cowl that normally is sealed and painted over. It may look intact, but can crack over the years and allow water to seep in. I've used some exterior 100% silicon 30yr chalk with good success.

I was worried this might be the problem. The cowl seems very difficult to peer inside though, there's the blank panel that blocks the passenger side and I'm guessing the leak is under it. When you used caulk did you, in a sense, "spray and pray?"

Originally Posted by Schurkey;

For whatever difference it makes, does the truck cab stay hot in the winter and cool in the summer based on heater/AC use? My cab was cold with the heater on, and warm with the A/C running. Had a MASSIVE outside-air leak into the cab where the steel of the body transitions to the plastic of the HVAC blower housing. Foam gasket completely rotted out, and it was a hateful job to replace. The '88 service manual gives the WRONG instructions. I had to refer to the '88 service manual SUPPLEMENT for correct procedure.

I think i remember reading a post about when you did this. Unfortunately, haven't driven the truck enough to know, i just got it a month ago and its mostly been sitting in my driveway, right now the interior is stripped. I can throw a seat back in and check?

Did this job require you to take apart the dash?


Thansk,

Alex

[aleekat]

I was worried this might be the problem. The cowl seems very difficult to peer inside though, there's the blank panel that blocks the passenger side and I'm guessing the leak is under it. When you used caulk did you, in a sense, "spray and pray?"

No. Looked for the seam and sealed it..

[Schurkey]

Originally Posted by ASJT3

I think i remember reading a post about when you did this. Unfortunately, haven't driven the truck enough to know, i just got it a month ago and its mostly been sitting in my driveway, right now the interior is stripped. I can throw a seat back in and check?

Did this job require you to take apart the dash?


Thansk,

Alex

Dash drops down on a pivot AFTER you completely remove the steering column and take off the dash pad, computer, glovebox, etc. Eventually, yes, I completely removed the dash. Blower fan box comes out with extreme difficulty. Original service manual says you can pull it right out--WRONG. Lacking about 1/2" of clearance due to piss-poor design. Supposedly have to discharge A/C and open the system to remove plastic plenum, I managed to attain "HULK...SMASH" mentality and brutalize the thing into submitting without opening the A/C system. Once apart, EVERY FOAM GASKET was entirely rotted--they looked good until I touched them, at which point they turned to "jelly" and became useless. Replaced EVERY gasket with Home Improvement Store adhesive foam insulating tape carefully cut-to-fit.

This sealed the air leak, the truck cab is now toasty-warm with the heater on, and today was -11F.

My truck was down for a month while I attempted to figure out why the service manual procedure wouldn't work. Then I stumbled onto the service manual SUPPLIMENT. I bet the 1989 and newer service manuals have the correct procedure, my 1988 truck and service manual were first-year-of-production for that body style.

I just now found the photos I took of that job, and posted four of them in the original thread: http://www.automotiveforums.com/vbul...1&postcount=10

[Vanfan]

Make sure all the screws are in holding down the plastic cowling, If you remove the right or left corner piece, there will be another smaller screw under that cowling corner.. They are usually left out by a lazy auto glass installer who looses the screw, or is to lazy to put it back in, and can create a leak into the right side cab floor board...

[Frankp87]

Vanfan described the location of the leak I had. After a good rain I would have one or two small puddles on the passenger side. I removed all the screws that retain the cowling down, put silicone in each of the screw holes and put the screws back in. No more leak. Hopefully that is all you need to do.

[ASJT3]

Originally Posted by Frankp87

Vanfan described the location of the leak I had. After a good rain I would have one or two small puddles on the passenger side. I removed all the screws that retain the cowling down, put silicone in each of the screw holes and put the screws back in. No more leak. Hopefully that is all you need to do.

This sounds a lot like my issue, however, I'm not sure I understand where these screws are. Are you talking about the screws that retain the black plastic cowl vent cover? I don't understand how sealing these screws would help as water can still easily pass through the vent to the open area underneath and (ideally) drain through the duckbill.

Can you clarify/provide a pic of the screws you're referring to?

Much thanks,

Alex