Damn water leak.

New user here, I have an 89 Cab Plus that has a wet/damp passenger floor that is killing me. One leak I found looks to be a faulty windshield install which stinks because it looks to be a new windshield. The second leak looks to be coming from where the blower motors mounts to the underside of the cowl. The foam seal is wet and you can see a little drip. I know on some cars they have drains in the cowl for when water gets in there. I can see two louvered panels in the cowl one on the drivers and another on the pass side and the center one is missing or maybe it's not supposed to be there. Is there a plastic cover that is suppose to go over the fresh air intake that keeps water from coming in? I may take the cowl cover off this weekend but I wanted to ask you guys before I dive in. Thanks in advanced. BTW I will post some pics in a bit.

I can't help ya with the windshield, it's very tricky to remove these. Tried with a friend on 2 parts trucks and both ended up getting cracked, it's the way that the chrome trim goes around them that makes em not the easiest.

The second leak I CAN take a decent stab with. There is a drain hose that is at the bottom of the evaporator. What can happen over time is that it can get clogged with dust and turn into a soupy mud. What I have done in the past is to remove the entire plastic housing from the front side and clean it off. I don't have any pics to show of this (sorry) With this cleaned up you can now follow the clear hose and poke it clear, then the other end of the hose goes through the firewall. There should be some sort of rubber grommet around this to help keep rain water OUT of the cab.

Another leak that I have experienced here was due to bad seals around the dash vents. The ONLY way to fix this kind of leak is to remove the dash and to put on new seals. I used weatherstripping found at Home Depot in the hardware department.

A third leak is from the grommet that houses the wiring for the ECU. Being the type that likes to tinker, I have removed this and used my own wiring harness (on a MS-1 build I did years ago) and it never sealed quite the same again since then. There is also another grommet on the driverside that people like to route floodlight switch wiring through. If you ever poke it out and don't put it back in perfectly YOU WILL HAVE RUST within 2 years (ask me how I know this)

Be careful with this. If you ignore it this'll happen:

Thanks Emjay for the heads up. I did do a little more legwork this morning and I think I may have one of the two leaks tracked down. Fist I pulled the cowl off to get a better look, good thing I did about two cups of pine needles, some moss and a few candy bar wrappers, dang mice. I kept wondering why pine needles, moss, and other stuff would come out of the vents when the fan was on high now I know. On the pass side is the intake for the fresh air and the seam sealer to it is lifting and there is some rust too. I then notice that if I pull the wiper motor out you can see the air intake. I wish I had done this first. I took a hook tool and lifted/scraped all the loose seam sealer away and can see what seems to be where the water is entering. Now I have to wait for it to stop raining so I can treat the rust and reseal that area.

here's something that I did to help prevent the flow of leaves and needles into the cowling area. some window screening and some RTV silicone and about 10 minutes with an exacto knife got me this:



I cut pieces of screen for all the available holes (appears that there were different options available internationally for wipers and such, that's another topic) including the ones with the covers. To fit the covers I cut a little bit of extra slack for the screens and small Xs for the screw holders to be secured to. I can not claim credit for the window screening material idea, that's from a fellow MT in Florida.

As far as your rust is concerned, that's minor stuff. You will wanna treat it with the wire wheel and prime it none the less, but you seem to have caught this when it was in it's infancy. Use the Rustoleum Stop Rust primer once you get rid of the rust and clean the area, it'll kill any micro cancers that you are likely to miss without sanding (that's what I used and I even sanded it, not a knock of skills at all.)

emjay,
How did you get that panel off to have access to do this? I have the same problem. Thanks.

open your hood and look at the edges that lye under the hood at the firewall... you will be able to find all the hardware you need to pull out. most are philly's head screws, and some may be just push in plastic tabs... in which case you gently pry under them with a thin small flathead, or 'trim puller' tool if you have one. some are a combo of both, in which case you gently remove the plastic philly's head screw, and then pry/wiggle the 'base' up and out.

the wiper arms, remember how your wipers look/where they are now in alignment with the windshield. and they have a plastic cover that you wiggle off, that hides the nut that holds them on if i remember correctly... (i need to pull mine to paint my wiper arms soon actually)

I forget if the fenders need to come out or not for this as well. It might be the other way around (cowling need to be off to get to the fenders.) But yes, he sumed it up well. I also would recommend raiding a JY truck of the plastic piece that covers the vents because it is a great insert to go in. For some reason Mazda only included one of these covers per truck.