Fluid Leaking in Floorboard

no pictures but a heater core is a easy job,the hardest part is the heater hoses.The clamps are on the passenger side of the firewall.I cut off the old tubes off the old core and and attched to the new core so i could put the hoses/clamps on from the engine compartment

Heater cores, ICK. They are always a labor intensive PITA. But if the A/C was an add on, it won't be so bad.
You'll have to drain the coolant, remove the heater hoses under the car, and split the case under the dash. It just clips together. You can either use the right tool, or a screw driver to get it apart.
You might want to remove the passenger seat as well, for more room.

your heater core is probably the culprit. This job if a pain and I'll bet the previous owner just let it ride if it didnt show any leaks.... This is just a good practice to replace the core when you've got the dash torn down.... Check your hose clamps at the outlest as well, if they're loose or stripped it could cause a leak as well.

Good luck!

You say the PO added A/C...is it a stock style system that sits under the dash at the center, or is it one that replaces the stock heater box up under the passenger side dash? OR, is this a factory A/C car that had the A/C restored? If the stock heater box is still there, it will be easy to pull it down and replace the core. Also, check the fitting in the intake for the one heater hose after you repair it. It should have a short tube attached to the part that stickes into the intake that reduces the pressure through the heater core so it won't burst. Someone may have replaced that fitting with a brass elbow without the extension tube. Anyway, fiure out what A/C system out have first.

kttrucks said:

Check your hose clamps at the outlest as well, if they're loose or stripped it could cause a leak as well.

Good luck!

Click to expand...

good call, a llose clamp is still a pain, but easier

There is a restictor in the elbow that comes off the intake manifold likely needs to be changed if it looks like it's been there for a while. They rust out and it allows the heater core to be overpressurized when you rev the engine, causing you to destroy heater core after heater core. Before I fixed this, I changed DOZENS of these (I've had my car since 1984).

Before I added AC I could do a heater core in about 30 minutes flat. After AC? Much harder. About two hours. Either way, the hardest part is attaching the hoses to the heater core. It's almost impossible to do it in the car and not have them leak. However, if you'll sacrifice two dollars in heater hose it's a snap.

I think the easiest way to do the heater core is to disconnect the hoses on the engine, unbolt the fan motor (inside the engine compartment), disconnect the heater control cables, remove the defroster vents, unplug the heater control unit, and unbolt the retaining bolt that is right behind the heater control unit under the dash near the PS kick pannel.

If you have AC pull the two bolts that hold the underdash piece first. Try to swing it aside to gain access. You don't have to remove it.

Disassemble the heater box and change out the core. Reassemble.

I get six feet of heater hose from the auto parts store. I mark off one end to the same length as the top heater hose with a silver Sharpie, and then do the bottom the same way. DO NOT CUT THE HOSE.

Loop the hose (marked but not cut) through the holes from the engine compartment back into the car, putting the top hose through the top hole, the bottom throught the bottom hole. Pull the hoses all the way into the passenger compartment. Reattach to the heater core assembley, the heater motor, the cables, the AC.

Now cut the hoses (where you marked them) and reattach.

A 5/16" deep 1/4 drive socket w/ a 6" extension and a ratchet works much better on hose clamps than a screwdriver. I have a section of about 18" stashed in the trunk in case I need to bypass the heater core in a spot.

The posters above have offered some good advice.

I recently did a heater core write-up with pics. See if this helps:

Heater Core Installation for 65/66 Mustangs - FordMuscle.com Forums