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Coolant leak under car?

4K views 23 replies 11 participants last post by  68Ghost 
#1 ·
This just started happening. a fair amount of antifreeze is leaking out the bottom of the car. in two places. the last pic looks like the previous owner already tried to seal it up with some kind of foam? the other spot where the majority of it is leaking looks like a hole or crack. does it flow through that area? what is that spot exactly and is that a big job to fix?
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#2 ·
That would be your heater core leaking up under the dash on the passenger side. Take a look. I doubt it's been leaking that long....you would have known it.
 
#5 ·
The "foam" is actually old sealant which appears to be no longer sealing. Lucky you because if it was it appears you would otherwise have a small swimming pool of green in the passenger floor. I expect it is soaking as it is.
You might like to remove that plug as is makes a convenient drain for cleaning up. You can buy a full set of new ones pretty cheap if the original is cruddy. Also you will want to use some kind of new seam sealer upon replacement. Like as seen in your picture but hopefully a bit neater.
 
#6 ·
The "foam" is actually old sealant which appears to be no longer sealing. Lucky you because if it was it appears you would otherwise have a small swimming pool of green in the passenger floor. I expect it is soaking as it is.
You might like to remove that plug as is makes a convenient drain for cleaning up. You can buy a full set of new ones pretty cheap if the original is cruddy. Also you will want to use some kind of new seam sealer upon replacement. Like as seen in your picture but hopefully a bit neater.
after double checking, the passenger floor does seem a little damp. but not too bad. what plug should i remove? that last picture is just a hole with a soft spongy material. kinda like a vent duct.
 
#7 ·
Remove the front seats and front carpet section, you'll see two Phillips screws holding the oval plug in the floor pan. Remove and replace the heater core. Be sure your carpet is fully dry or replaced before you put it back or you'll have even more rust problems.
 
#9 ·
I just pulled up the carpet from the passenger side and found this. looks like previous owner just threw some cardboard under there. i dried up the puddles and i'll order a plug. looks like the leak is coming from that black rubber hose in the top of last pic. should that have clamps on it? should i replace that?
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#10 ·
So a PO cut a beer can open and used it to make a patch!! They actually make a plate that fits over that oval hole and is held in place with 2 screws.

I do not know what that rubber hose is. Can you take a photo farther away from it?
 
#12 ·
haha thats what it looks like! i tried to find a date on that box. its a flat peice of beer box with a flat layer of aluminum under that. looks like he cut an actual beer can and layed that under it as well. the black rubber hose is all the way up in the top left corner near the console
 
#14 ·
The black hose is the air conditioner condensate drain and you should consider yourself lucky... the heater core looks like it's been leaking for a while and without the a/c hose your floor would have been the main repository for all that coolant. The heater box will need to come out as the heater core is located inside.
 
#15 ·
i removed my a/c condenser when i replaced the radiator recently. i didnt put it back since the a/c isn't working atm. i did remove a long hose from that general area from that box inside the engine bay to the condenser. could that be causing it to leak?
 
#17 ·
Maybe the heater case / box will still be in good shape. You can get a heater core from a local parts house or from your Mustang parts vendor. I recommend rebuilding the case with an inexpensive Daniel Carpenter foam kit from the vendor. Here's a photo of the last one I reconditioned, before and after.
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It's also a good time to do a cooling system flush and fill, replace any and all hoses if needed. And the floor pan...welcome to the Domino Effect, also known as "project creep" with your VMF buddies !!
 
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#19 ·
Here is an article on changing the heater core. Its not hard, just kind of cumbersome working underneath the dash.


You can bypass the heater core in the meantime if you wanted to continue to drive your car around.
 
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#21 ·
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So you should see this in your engine bay, the middle picture. You just connect your hose from your water pump to your intake instead of going inside to your heater core and back out. Then once you replace your heater core, reconnect it back up like normal.
 
#23 ·
With your '67 with factory air, your whole HVAC system integrates heat and A/C. That makes things more complex. There are four vacuum motors that actuate "doors" within the HVAC system under the dash to direct heated air to the floor outlet or the defroster, blend outside air with inside air and direct A/C to the center and outboard dash vents. Those motors are controlled by the left hand slide lever on the heater control. It gets a little complicated and everything is harder due to it all being under the dash. There is also a vacuum motor (above the heater core inlet/outlets) attached to the firewall in the engine compartment that turns off the hot water flow to the heater core when the A/C is on.

Here are some good diagrams that show how this all put together. If you want the heat/defrost and maybe the A/C (someday) to all work in harmony, all this stuff has to work properly. If you want just the heat and defrost or just the heat to work, not all of it has to work. This is for a 1968 but I think the '67 differs only in that the check valve for the reservoir is not in the canister but inline in the hose that goes to the canister.

And this does not address getting the heat/AC box out to replace the heater core. That is also more complicated with A/C. Also, to get to the vacuum motors, you will need to take the seats out, the console out and the steering wheel off for the easiest access to everything. To do it right, is a major job and not for the inexperienced. If you do not drive it in the winter, and if you can live without A/C maybe just blocking off (with rubber caps) the manifold outlet and the water pump inlet is the way to go. Or, loop one of the heater hoses as mentioned above.
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#24 ·
I was under mine a week or so ago, and noticed a slight bit of green in that drain tube. Looks like it all needs to come out. May just block off the heater for now, upgrade the whole ac system at some point.

Good Luck!
 
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