TJ water leak behind firewall

    I have a significant water leak that appears to be running down the inside of the firewall. (Thank goodness for drain holes!) I'm fairly sure it's related to the recent addition of the louvered hood panel, but it's not the panel itself that's the problem. When I had my hood painted, I think the body shop removed the hood and cowl. Why the cowl, I have no idea. I just noticed that the rubber grommet that runs the width of the engine compartment between the cowl and hood has been pinched and isn't correctly installed -- thanks to the carelessness of the body shop. A couple of questions.....


    First, it seems obvious, but I'd like to know if that could indeed be the problem? That is, could water running down between the hood and cowl make its way into the passenger compartment? If yes, then I'm onto to something.


    Second, while I'm reinstalling this rubber piece, is there any value to running some caulk (silicone?) somewhere just to give an insurance policy against leaks? If so, best product to use? Thanks all! Chief

    When engaged in conversation with a fool, be sure he is not similarly engaged.
    Chief, DEJA Grammar Police

    Definitely not the heater core -- that's virtually brand new.


    I will remove the cowl and see what I can see. Nobody answered my basic question, though. Can water that gets in the gap between the hood and cowl make its way into the passenger compartment? In other words, is that rubber gasket/seal really important for leak purposes?

    When engaged in conversation with a fool, be sure he is not similarly engaged.
    Chief, DEJA Grammar Police

    I dont think it is. I think that's just to seal up the hood were it hinges because you have some electronics and sensors in that area. The cowl is made for water to run through it, the louvers in the cowl allow for water to run through. I would pull the cowl and make sure it's not plugged some how and getting water build up. Mine did that once and decided to dump water through the dash on a hill climb. It also could be somewhere around the windshield or frame that's leaking down the back of the dash. I'd try to hunt down the leak. Probably won't be easy to find just because of all the possibilities where a tj can leak.

    When they removed the cowl if they didn't install it correctly you can and will get water into the passenger cabin of the Jeep. Most of the time it is right on the passenger floor board and it is NOT the heater core. When you take that cowl off you also disturb the seal around the air intake for you blower motor. If that seal is not re-installed properly you will have leakage.

    1 - Have you checked to see if the cowl is draining properly? There is a rubber drain at the bottom of the cowl that is famous for being clogged. If that doesn't drain then you'll get water building up in the cowl area and that will leak through into the cabin. Usually a straightened wire clothes hanger is needed to ensure it is clear through and through.


    2 - The condensation drain is also known for leaking back into the cabin of the Jeep. It is the drain that you typically see dripping moisture on the ground during the summer when the A/C is running. It has a tendency to sometimes catch wind while driving and push the condensation back up in to the Jeep instead of draining out and onto the ground. This could be a possibility since the A/C is used quite a lot in the winter to clear the windows when on defrost. The fix for that is to face the drain a different direction so the wind doesn't hit it directly - had to do it to my TJ long ago.


    A thing to note is that both of these problems will cause water to accumulate in the cabin and typically on the front passenger floor area.

    Follow-up: This past weekend I removed the hood and cowl so I could gain good access to everything. I used a silicone caulk around anything that looked suspicious inside the cowl. Still, the leak persists!!


    Quadna, by coincidence I did use a straightened wire clothes hanger, and I was able to poke it all the way through the cowl drain tube so I could see it sticking out underneath. I'm sure it's not clogged. However..... I noticed that the spot where the tube meets the plastic basin inside the cowl is not tight. If I poke the top of the tube, it'll jiggle a bit. This may be perfectly normal -- I don't know how the tube is connected to the basin. Does the basin have a little nipple on it? Is the tube slide onto this nipple and is held in place just by pressure from a male/female type of fit? If that tube is supposed to be rock solid -- no movement -- then I may be onto something. It seems impossible for a regular person (read: someone not a Chinese contortionist) to remove the cowl drain tube to further investigate.


    I see no evidence of water coming in from the inside of the windshield, hardtop or door. I have not checked the AC condensation tube, but I believe the leak is also not related to my heater/AC; it occurs when the TJ is just sitting outside in the rain. And I really don't see how my new louvered hood panel could be the culprit. For now, I've simply removed the passenger-side floor plug. This is really a bummer.

    When engaged in conversation with a fool, be sure he is not similarly engaged.
    Chief, DEJA Grammar Police

    Quote from quadna


    Maybe it's running through the windshield? There are holes near the top where the rubber seals mount up that could be leaking. Water gets in the windshield, flows down, and runs out the bottom into the cabin. :shrug:



    Thats my guess too. Only because I know mine does the same thing.

Participate now!

Don’t have an account yet? Register yourself now and be a part of our community!

Register Yourself Login