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Hey Guys,

I've changed out my heater core and im still getting leaks. I'm thinking i need to replace the seal on the drip pan. Is that a part or can i use just a sealant?

Thanks
 

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If memory serves me correct, the base/lower piece of the heater core/evaporator cover has like a U-Shape to it where it mates to the upper half having a straight piece.

I had to play with that fitment about a half dozen times, 'till I figured out the evaporator core was shifted and the condensation was falling directly on that seam.
 

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Hey Guys,

I've changed out my heater core and im still getting leaks. I'm thinking i need to replace the seal on the drip pan. Is that a part or can i use just a sealant?

Thanks
No amount of seals or sealant will stop a leak due to a missing A/C Drain Elbow.
 

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Discussion Starter #4
Elbow isn't missing. I may need to just play with it some more. There was some type of seal around the cover.
 

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Discussion Starter #6
Guys i found where it is leaking. Its not the seal that connects the upper and lower Heater Core housing. Its coming directly from the firewall where AC condensation drains.
 

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Impeded BEFORE it gets to the outside elbow?
 

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Thinking the same thing. Make sure that the Port is not Clogged and also that the little elbow fits snug and that water is not seeping around it and findings its way back into the car.

Instead of the elbow, I replaced it with some old Heater Hose I had laying around. I plut a band Clamp on it so it wouldn't fall off. An added benefit is that the water doesn't drip all over the frame now and just drops to the ground away from the car.

Here is a pic of that hose under the AC lines. Little shorter than I wanted but all I had at the time and was an old faded 9C1 Heater Hose that was ***-colored anyway.

 

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If memory serves me correct, the base/lower piece of the heater core/evaporator cover has like a U-Shape to it where it mates to the upper half having a straight piece.

I had to play with that fitment about a half dozen times, 'till I figured out the evaporator core was shifted and the condensation was falling directly on that seam.
Could you elaborate on the shifted evaporator core a little?

I am banging my head against the wall trying to figure out my water leak problem. It's not the usual missing elbow issue. It's not coolant. It's not rain water. I resealed the evaporator/heater core housing. The water appears to drip off the bottom of the foam backing that surrounds the hole that the drain pipe goes through in the firewall.

Thanks for any tips.
 

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I have had a persistent leak into the passenger's side foot well for years. I have tried everything. I have found a leak under the windshield, my door to body wire channel was loose at the door, and the seal over the cabin air intake was warped. I also found my antenna cable grommet was totally out of the hole. Check the flap at the end of the drain channel across the front of the firewall that goes under the cabin air intake hole. Make sure your door seals properly...a dollar bill should have resistance when removing it from between the door and seal with the door closed.


I have sealed everything conceivable on the firewall.


I also tried pressurizing the car with a small shopvac. I put the shop vac in the car, and made a "window" seal (wing window on a wagon), taped it to seal it, I also sealed the air inlet hole in the firewall, ran the suction hose, and wire through the seal, and started the vacuum from the outside. I sprayed the whole firewall area with "bubble liquid" from the dollar store. Wherever there are bubbles is a leak.


You can also try putting some new butyl caulk in the attachment channels for the top door seals (I do not think this is the cause, but it may be the reason my seatbelt gets wet in the rain...I can hear it dripping). Check behind the side windshield reveals for gaps in the urethane.


Roofing cement or sealant works good to seal things, and is cheap.
 

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Thank you Fred for the quick reply and good advice. I am quite certain that this particular problem is not a rain leak issue, but water coming from the AC system. I'll tell you why. The car lives in the garage. It is not my primary vehicle, and since I've been trying to figure this problem out I have purposefully been avoiding taking it out in rain. If I turn the AC off, there is no water leaking. The water will come consistently from the firewall side of the evaporator/heater core housing on any drive over 10 min long whenever the AC is used, more so in warm weather.
 

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If that is the case, you definitely have a leak at the tray. Exactly where is now the issue Check for cracks and holes Make sure you do not have a wire or hose trapped between the pan and the rest of the duct. There is a part of the pan that does not have a seal on it toward the rear (front of the car) above the drain tube. Perhaps you can put some silicone on that area. Make sure you have all of the screws in tight. Have you pulled the carpet back, and had someone ride along to check where the water is actually flowing from, or at least idle it, and watch with the carpet pulled back?


If the opening for drainage is even partially clogged it could back up the water until it flows out of the unsealed area above the drainage hole.
 

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Could you elaborate on the shifted evaporator core a little?

I am banging my head against the wall trying to figure out my water leak problem. It's not the usual missing elbow issue. It's not coolant. It's not rain water. I resealed the evaporator/heater core housing. The water appears to drip off the bottom of the foam backing that surrounds the hole that the drain pipe goes through in the firewall.

Thanks for any tips.
Okay, the problem I had was easy to see as the condensation from the evaporator core was coming down right at the left hand side where the upper and lower halves meet.

What I did was use some 1/8" pieces of rigid foam to move the core to the right hand side of the vehicle just a little bit so the edge of the core was was away from the seam.

Can you visibly see any of the condensation dripping from any areas? I used news paper to be able to help see where exactly the drips were coming from?
 

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Okay, the problem I had was easy to see as the condensation from the evaporator core was coming down right at the left hand side where the upper and lower halves meet.

What I did was use some 1/8" pieces of rigid foam to move the core to the right hand side of the vehicle just a little bit so the edge of the core was was away from the seam.

Can you visibly see any of the condensation dripping from any areas? I used news paper to be able to help see where exactly the drips were coming from?
Where the upper and lower halves of the plastic housing meet? I'm not picturing that very well as the housing has two compartments: the evaporator in the right compartment and the heater core in the left compartment, with an internal wall separating them. If the evaporator was displaced to the left, it would be over the seam on that internal wall. How did you see that it was leaking there?

When you said your evaporator was out of place, I was thinking that would make sense if mine was out of place towards the front of the car and dripping on the front, unsealed part of the housing. It looks like the drip is off the firewall side of the housing. It looks like the evaporator is in it's proper place to my eye, though.

I removed the bottom of the housing to try to see how the water is falling.In the picture below, how the water is dripping off the bottom of the foam is exactly how it looks when the housing is in place.

BTW, the black Caprice on your signature looks exactly like one I used to own.
 

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If that is the case, you definitely have a leak at the tray. Exactly where is now the issue Check for cracks and holes Make sure you do not have a wire or hose trapped between the pan and the rest of the duct. There is a part of the pan that does not have a seal on it toward the rear (front of the car) above the drain tube. Perhaps you can put some silicone on that area. Make sure you have all of the screws in tight. Have you pulled the carpet back, and had someone ride along to check where the water is actually flowing from, or at least idle it, and watch with the carpet pulled back?


If the opening for drainage is even partially clogged it could back up the water until it flows out of the unsealed area above the drainage hole.
I think you may be right that the solution may lay in sealing the firewall side of the pan. I am not sure how well that will work as it's not really designed in such a way that it is easy to make that watertight. I have no idea why they designed it that way.

FYI, the drain wasn't clogged, there aren't any cracks or holes that I can find anywhere on the pan/housing and my first attempt to fix this was to drop the pan and reseal it with silicone gasket maker.

I also was thinking it could be condensation on the outside of the pan, which does seem to be excessive, at least here in super humid Houston. I actually insulated the pan and as much of the upper housing as I could access, but it didn't make much difference. I also have a far fetched theory that the drain tube itself gets condensation on it, which drips down onto that foam around the firewall hole and then down onto my floor (the drip is visible off the bottom of that foam, see the picture in my last post). When I removed the pan, I did an experiment with filling the pan with ice. When it melts the very cold water simulates the very cold water coming off the evaporator. It caused condensation all over the bottom of the pan just like when it is installed AND it had the condensation on the drain tube itself. I don't like this theory because: 1) I don't know how to fix it, 2) doesn't seem like that would be enough water as I find on my floor and 3)it would mean this is not a malfunction but a design flaw, in which case every one of these cars would have the same problem, at least in hot and humid locales, and this does not seem to be the case.

Just in case you're curious, I have been driving it with the pan unattached but placed so as to tilt and drain into a small tub so I could try to observe how the water flows inside the housing. On a 20-30 min drive with temps in the low 80's and high humidity, the AC drains about 1.5 qts of water.
 

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I went ahead and put the pan back in place with new RTV seal and a liberal amount of silicone caulk on the firewall side of the pan. I'll let it sit for 24 hours or so and then see how it works. I am having a hard time being optimistic about this issue. I am still not clear on why I am getting water coming down the firewall side of the pan and am worried that even with the caulking on there, any water that makes it onto the foam padding between the pan and firewall will just flow through it and out the bottom. We'll see!

Thank you Fred and Junior for the tips.
 

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Good news, I am declaring my car's problem resolved! I have driven it in both high humidity and high temperature conditions on drives of at least 30 minutes and there is no trace of water leaking.

I don't know exactly what was causing the leak. Apparently the water was coming in between the unsealed firewall side of the drip pan and the foam padding that it presses up against on the firewall. Why it was doing this I can't say for sure. I think it somehow was dripping off the evaporator and down the front part of the inside of the housing, probably the inside front right corner based on the observations I made when I drove the car with the pan removed. It disturbs me that I couldn't find anything out of place or necessarily wrong with the car to account for the problem. I think it has been going on for quite a while. Ever since I bought the car 3 and a half years ago, there was a vague moldy smell that would be noticeable when parking the car with the windows closed for any length of time. It wasn't strong or nasty enough to bother me to the point of thinking something was wrong with the car. I chalked it up the natural scent of the car and fabric interior. I didn't notice the wet floor til I was trying to figure out a separate problem, which turned out to be the evaporator freezing up. The insulation under the carpet was soaked, but the surface of the carpet was dry. Fortunately the floorboard is not extensively rusted, just a little bit in a couple of places.

I'd urge all b-body owners to check under their carpet and make sure it is not damp. The way the water leaked on my car, it went behind the carpet on the firewall and down to the floorboard with no evidence on the top of the carpet that there was a leak.
 

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[SNIP]

I'd urge all b-body owners to check under their carpet and make sure it is not damp. The way the water leaked on my car, it went behind the carpet on the firewall and down to the floorboard with no evidence on the top of the carpet that there was a leak.
This is exactly why I have a piece of clear vinyl tubing going from the elbow, down below the frame.

I will usually take a look at the ground when I park my car, and see a nice puddle and a good stream coming from the tubing.

Glad you got your problem resolved. It's a great sense of accomplishment when you're able to track down and fix those pesky ones.
 

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This is exactly why I have a piece of clear vinyl tubing going from the elbow, down below the frame.

I will usually take a look at the ground when I park my car, and see a nice puddle and a good stream coming from the tubing.

Glad you got your problem resolved. It's a great sense of accomplishment when you're able to track down and fix those pesky ones.
Yes it is a good feeling! I will be keeping the trim off the carpet edge for a while so I can check under the carpet for moisture, cause I'm not feeling totally trusting yet. I also had a tube running off my elbow and the leak never prevented water from also draining in the normal way. There was no tip off to the problem besides the vague, mild smell.

So, can you tell me a little about your black Caprice? It looks so much like my old car, it's spooky. Where did you get it?
 
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