Not practical to try to fix a heater core. Replace it with a new one.
Talk2DIY Automotive - 1986 Tires and Changing Heater Core was released on: USA: 14 August 2004
Replace the heater core. It is leaking.
If that made sense i'd answer it
osmobile delta88
Low coolant? Thermostat not opening? Control cable not working? Plugged heater core? Heater core "airbound"? Low coolant? Thermostat not opening? Control cable not working? Plugged heater core? Heater core "airbound"?
To change out the heater-core in a 1986 F-150, you must access the old heater-core through the glove box. You must remove the glove box by removing the screws that hold it in. Once this is accomplished, you must loosen the clamps on the hoses that are connected to the old heater-core unit. Then remove the hoses from the old heater-core and slide the old heater-core out through the opening where the glove box use to be. Install the new one using these instructions in reverse! Presto...installed! Mechanic Man
By the firewall, up and under the dash.
Loosen the dash and pull out the complete heater box after you have disconnected the heater hose from the firewall...........
Generally, the upper heater hose leads to the water pump.
just under $40.00 @ Advance auto
The heatercore itself is more centered under the dash.The blower motor is behind the glovebox.See "Related Questions" below for an excellent write-up on the 1986-1995 Taurus / Sable heater core