I just finished re-doing my carpet after it got damp last fall from over-zealous use of a pressure washer on the firewall. 

It rained very hard all day yesterday. Went out this morning to fiddle with the car and......the passenger footwell carpet is 

SOAKED. I did leave the hood open, could the rain have come in through the cowl because it was left open?

 

 

'88 GL D/R wagon

Shouldn't cause that.

 

I know it is helpful to turn off the HVAC system before shutting off the car.  That will close the flapper for fresh air inlet.  I do that at my house to keep mice out.

 

Not sure if that will keep water out though.

If its like my 89 it will. But I removed all the A/C plumbing and have two holes left over on the pass. side fire wall.

After tearing everything out again (fastest interior strip ever), it seems that the water was coming out of the join line between

the heater blower, and the a/c evaporator core.....so I think the rain was hard enough to come in through the fresh air inlet????

But the HVAC system was set to off, and both sides vents were set to a/c months ago, so still a mystery.....

Not coming in through the a/c line grommets, underneath the rubber cover (beneath the carpet passenger well) was dry, wet

was on top of the rubber.

Edited March 18, 201412 yr by SmashedGlass

Water will get into the cabin, by dripping through the joints in the plastic molding surrounding the wiper drive axles, and then directly through the cabin intake air vents below that joint. Japanese engineering at it's best.

Think I figured it. There was a very small machine screw (from where or what I do not know) that somehow ended up sitting on the cowl and miraculously wedged itself perfectly to fill the drain hole in the passenger side cowl drain hole. So perfectly, that it looked like it was supposed to be screwed in there. Debris had built up around it creating a perfect seal. When it rained, it rained buckets, and probably backed up and overflowed out of the depression there and straight down into the passenger fresh air intake.

 

Of course, I had already started to remove my plastic cowl parts by this time to make sure it wasn't an internal problem and, since the numb nuts who installed my replacement windshield managed to get it glued in a few spots with windshield adhesive, a couple of the molded on clips broke off...... So now I'm patiently (ha) waiting for new cowl parts to arrive in the mail. On the bright side, at least the inside of the cowl area is now very clean.

 

**ScoobieDubie, just about every car uses a similar two-part cowl setup. So I wouldn't blame Japanese engineering. I actually have heard more complaints about GM vehicles of the last 15 years or so having issues with leaking into the passenger compartment.

Edited March 19, 201412 yr by SmashedGlass

The lapse in good engineering, had to do with how close the joint between the two pieces was to the vent opening. It was two close so I used some black gasket maker to seal that joint.

I see your point; I was thinking of using something similar myself as the foam/rubber seal strips along the top and side edges pretty much turned to powder and fell off while removing the cowls.