I have a water leak running on my passenger floor that drips from the bottom of the heater box. I just replaced the heater core and evaporator core, so no problems there. The leak is definitely rain water.

I've seen a few threads where a water leak can be traced to the fresh air cowl intake, and that's definitely not my problem as I've run a hose and fished it back in the cowl and let it surround the platic intake flange completely without any water showing up.

The water shows up when rain water runs between the front of the cowl and the rear edge of the hood. When I pulled the heater box, I replaced the seals between the firewall and the box with brand new ones. Is there some kind of design flaw that allows water to enter around the blower motor?

Also, the previous owner had siliconed a section of black ABS pipe, cut in half lengthwise, to shape a gutter along the drip edge between the firewall and the cowl. He said he had read online that it was a good idea and decided to be proactive about it. I removed it when performing some work in that area, and am just now noticing the rain water leak, now that it is Fall and were getting rainy days... so I can't exactly draw a relationship between the two.

What gives?!

 

not sure if your still following this since i see your post was back in July but since no one answered, I will.

I did the same thing. replaced my evap core and heater core. then later found lots of rust and water on the passenger side floor. after much research i have concluded it is a design flaw with how the blower motor attaches to the firewall. i siliconed the **** out of everything and it reduced it by half or more but it still got a little wet. after fixing the floor pan i sprayed it with bedliner material in case it gets wet again.

the best option is while the dash is removed and you have better access to TOTALLY seal the **** out of that connection point between the blower motor and firewall.

that rain gutter might have helped, try to put it back.
i also ran silicon inside on that cowl to slow or redirect the water coming down away from that area.

my xj sits outside parked in the driveway. everytime it rained there would be a small cup worth of water on that floor board. thats the best i can tell ya bro. i made it alot better but never 100% fixed it. drove me nuts and i had to call it good with what sanity i had left. LOL

 

Thanks for the response! I basically settled on that same conclusion... its a flaw in the design. There's nothing missing from my jeep, and nothing else wrong or improperly i stalled in the area of that blower motor... and I can't imagine that it hasn't leaked in the same way since brand new.

I have my carpet completely out, and I'll be sealing the floor before I reinstall it. However, I don't want water to ever settle there again. If nothing else, for the sake of the carpet and insulation.

I think a fix that may work, is a small "hat" that can act as a shroud over at least the top half of the blower motor opening. It could be cleanly siliconed in place, so its removable for access to the blowrt motor. Imagine something resembling the top half or two thirds of a differential cover. See what I'm thinking?

I'll dig around and see what I can come up with.

 

Yeah I get exactly what your saying and I think its a great idea. it will shield the rain away from that area but still allow proper air flow. I think I will look around and see what i can come up with also.

I think my jeep was kept inside most of the time which made it a smaller problem on the floor pan than others. i lost all my pics of that project when my phone died but i had two small holes, one less than a nickel the other bigger than a quarter. I filled them with steel stick 2 part epoxy putty, ground it all down with a wire wheel and then sprayed everything with a rust converter like rustoleum or others make then i primed it, painted it, then sprayed with with 3M sealcoat bedliner like material. my thought was some water will still get down there but its not in contact with the metal and will evaporate over a couple days.

another thought i have while fixing it was to find the lowest point where the water pools and put a small drain hole. that way the water flows down and right out. i opted in the end not to but still could work. i was worried about snow and road salt effecting it from underneath.

 

I'm bringing this thread back from the dead as I am running into the exact same situation. Did you ever find a way to shield the blower motor area? Or another fix?

After reading countless threads about typical leaks, I fixed the small area on my passenger floorboard and began looking for the leak to prevent this from happening again. I did seal one area that some may miss. It is the area under the hood where the firewall meets the passenger fender. There was an area of seam sealer from the factory that had cracked and could be part of the problem. I used 3M Marine Adhesive sealant that was mentioned in some other threads. I also sealed the foam hood hinge seal to the firewall with some RTV.











After giving it the proper time to cure, I tested for leaks again. When I spray the blower motor with a hose, I am still getting a trickle from the bottom of the heater box inside. I don't see a way of sealing the inside (firewall to heater box) area and the foam seal seems to be intact although obviously not effective. Looking on the other side for 97+ it looks as though I may be able to put some sealant in the top half of the small channel on the firewall that the blower motor cage/housing sits into. The bottom half seems unreachable unless I remove some a/c components which I would rather not have to do. Anyone have any more experience or success with this?

 

I' m battling this same issue. I cannot keep the water from dripping out of the box onto the passenger floor. I haven't done much yet (just sealed around the fresh air opening under the cowl), but when we get some more consistent warmer weather, I will be fixing this issue, whatever it takes. I need to replace my evaporator core since my AC is so/so, and the heater core is a struggle to keep clean and blow hot air. So, not a whole lot of help, but I hope in the next month I will be tackling this thing to completion.

 

Pittman... I have long sold that XJ but I give you the short of what I found to be the solution with mine. I tested for water leaks by turning a garden hose on a low setting, and starting at the lowest points that water could be intruding, I worked my way upward. I started at the firewall opening of the air box, and though I do believe it is a fairly poor design, I had replaced my foam donut around the blower motor and it did not leak there.

I tried the areas around fender and firewall seams, and even though there were some gaps in the factory seam sealer, you can see where the pieces of the body are assembled, they used some kind of expanding foam sealer between them. Theses places never leaked on mine, though I took the extra precaution and sealed them with a seam sealer as you did.

I finally found the culprit when I moved the hose higher and began filling the cowl area on the passenger side. There is a fresh air intake vent that sits at the bottom of the cowl and allows fresh air to enter the heater box. There is no good way to reseal it without removing the dash and heater box... unless you cut a hole in the cowl beneath the vented plastic cover. This is what I did. Its the only way to get access with your hands to be able to apply a heavy coat if seam sealer around the leaking edge of the cold air inlet. I couldn't find much I do here on this forum, but I did find a good write up on a TJ forum. Theyre basically the same construction relative to the cowl/heater box area.

 

Thanks for the feedback. I found some threads about the cowl as well and thought that might have been my problem. So I tested that area and to my surprise it did not leak. It only leaks when I spray the blower motor. I guess I will try to use some sealant in the channel where the blower motor housing sits into but it seems unlikely that it would leak through that area the way it is put together.

 

GPXJ -When you do that job, do both new factory evap & heater core. get a new gasket for the blower motor against the firewall. when putting back together use that 3M sealant pictured and seal where the motor meets the firewall well.

Pittman- I solved my problem by parking it in the garage. LOL its the cold air intake sandrider mentioned / and or where the blower motor and firewall meet. good luck.

 

I cut a hole in the passenger cowl and slathered RTV around that fresh air intake as much as I could. I think I can rule that out as my leak. But the rest of the things in this thread I'm just gonna have to work through one by one. When I first bought the Jeep, it was collecting water on both side. I found about a 1/8" hole drilled in the drive side cowl area that was allowing water into the drive side. Weirdest thing, no clue why anyone would have done that....but I sealed it and that issue was resolved. Just gotta get this passenger side lines out so I can put the carpet back in for good.

 

Now that I think about it more, I didn't think my leak was coming from the cowl fresh air inlet at first, because I could run a garden hose into the cowl and get no leak from it. But it wasn't until I removed the cowl trim piece and fished a hose farther in toward the passenger side that I found it was in fact the air inlet leaking. This explains why it would mainly leak after a rain overnight when I was parked on my uphill driveway. At an incline, the water had a chance to run back and to the passenger side before it could drain out of the cowl through the driver side.

 

I think I may have finally found the source of my leak. I have not seen this suggested so I figured I would post here so it may possibly help others that are having a drip down their inside firewall where it meets the blower motor housing and foam seal.

As I stated earlier, I discovered that I was only getting the leak when spraying the blower motor under the hood. Many others have reported to have stopped the leak by sealing between the blower motor housing and the area it mounts to on the firewall. I noticed that the way it mounts on my 97 is different to how the earlier ones mount. So, after wrestling my blower motor/housing out I took a closer look.








I noticed the backside of the housing has a lip that seats into a recessed area that is actually part of the hvac box itself. I have a hard time believing that the water was traveling around these three opposing lip areas. After further examination, I saw a small gap between the hvac box and the firewall where I could see foam peeking through. This was also the lowest point where water would settle. So I used a long funnel to isolate that area and poured some water though it making sure none made it past where the blower motor would have been. Sure enough IT LEAKED!





After letting it dry I used some black RTV to seal the gap between hvac box and the firewall at the bottom and along the seam up to the half way point on each side.




I am letting it cure for a few days before testing, but I am fairly sure this will take car of it. Will report back when I test it.

 

Great photos. I think you nailed it!!

if the water were able to sit there long enough it would eventually leak through that foam seal. You figured it out!

 

After waiting a few days I went out and tested it again. I am happy to report no leak! Hope this helps the 97+ owners that are having this same leak.

 

Nice! Thanks! Yea, I cut my cowling for nothing. Was the seam sealer in the corner AND the blower. Btw, my big mistake was to not let the hose run long enough on the blower. When I saw no leaking after a minute, I moved on. Turns out mine needed at least a few minutes to start dripping.