Coolant leak help needed please

[Indytona675]

1999 4.6
I believe I have a bad heater core. But I can't quite see the leak. Coolant is running down fire wall and dripping off cat conerter shield ONLY when heat is Turned ON. It will Not leak when controls are set to OFF. The heater core lines are dry. I can't see a weep hole. Im curious what you all think before I spend a day ripping the mother loving dash out. I HATE doing heater cores.

 

[qcksnake]

Sounds like you got a heater core leak, The most likely reason it only does it when the controls are on is when you turn on heat it opens the flapper door to the heater core. Then the excess water exits the ac condensation hose, Which if I remember correctly is a small 5/8 hose that comes out the rear of firewall and is tipped down over the cat sheild just like your describing.

There is a youtube video of a f150 heater core removal, Other than the console its the same for the expedition and will save you some time if you never done it before.

OHHH and do yourself a favor and get a ford heater core.

 

[Big White]

I would put some dye in the system and check very carefully around the heater hose connectors where they connect to the core on the firewall. You may only need the hose repair kit which has the connectors and new o-rings. If you're lucky that's all it is, the heater core is rather involved to get out.