Water comming in! Man the life vests!

Sal Lubrano

Active Member
Apr 26, 2002
When it rains I have water comming in from the heater box. It is comming from the area where the two halves of the box join together. This is the way I purchased it and it seems like the previous owner tried to stop it. Does anyone know what is causing it? A bad seal maybe? But which one? I need to place a towel on the floor when it rains so I don't get the ecm wet.
Thanks for any ideas.


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Did you verify the drain hole is open in the engine compartment PS side?

You will need to remove the fan motor to get to it. You will see (Trying to recall and explain) the heater box "going down" along the firewall. At the bottom of it (sick a long screwdriver in the box ad move it around) there is a drain hole. Mine was plugged pretty much close to 95% with dust that turned into hard mud. After the rain, or washing the car, it would drip from "somehwere" for days/weeks! Now, no more drip......... drip ......... drip ......... If ithe drain works, you should never really get water sitting in the box. I would try that.
Pull down the rear of the r/f inner plastic wheel well and open the drain with a coat hanger or small screwdriver. It gets plugged with sludge.
Drain was clean not a think in it. I did notice a smaller hole the size of 1/4 inch under the heater core could this be a problem? Also I noticed the main door right behind the drain stays open (up) when I leave the a/c on after the car is shut off. Could there be a seal there and it letting water right in?
Look here to see what I am trying to explain.

So you took that cover off according to the instructions on that site? Did you make that dam to prevent any water that accumulates in the well from draining into the vent box? You are sure you sealed the cover correctly? I used 3M's rope seal and it works and looks factory.
I had the same issue. I pulled the carpet and siliconed everything.

One step better, take the ecu and put it up in the glovebox. (either modifying the box or removing the box and having the glovebox door as an access point. It'll be harder for water to get on the ECU if any water managed to get in...
3M Strip-Calk pn 051135-08578 (black) 20 yds. in 1' lenghts. I used about 1/2 the box. I got mine a local parts store that also sells auto body supplies. It was in that area. You should be able to find it in an autobody supply store. I don't remember the cost but it was not expensive and is the perfect solution to sealing the box.
one last question. Should I place some caulk under the cover or mount the cover with the old seal and place some caulk over the outside? My seal is ripped pretty bad in two. I want to replace it as well.
I cleaned off all the stock sealer off the lid and wall. Some of it was crusty but most was still pliable. A paint scraper works fine to separate the cover (make SURE you have all the screws out as per that website). If your cover has been off before and they used silicone to put it on your going to have to slice that off. After I test fitted the cover to see the clearances I put the ropes along the cover in 1 or 2 layers to fill the gaps. Once the lid was down and secured I smoothed out the bead (easy to do with your finger) and added any that needed to added. You could also use the rope caulk to make that dam down in the pocket that the other website showed. I didn't bother with that. Take your time and you'll be fine. Remember make sure you have all the screws out or you will snap the cover like I did when I was wedging it off. I just sweared at myself and then glued it back together. :wink:
Thank you everyone for your help especially Pronto. The 3M strip seal is a perfect product and highly recommended for this job would not have used anything else. I sprayed the area down with a hose and left the car in the rain and all is dry.
Good work! :) Alot of guys use silicone but I don't like that. Its too hard to remove if you have to and it's way more messy. The rope strips are handy sized and it is easily moldable. Clean up is no problem either.
Pronto said:
Good work! :) Alot of guys use silicone but I don't like that. Its too hard to remove if you have to and it's way more messy. The rope strips are handy sized and it is easily moldable. Clean up is no problem either.

Trade name is dum-dum or strip caulking. Comes in white, black, or gray.