1mustang

i have an 86 gt vert....im guessing my heater core is leaking...when i turn on the defroster i get a fog or smoke coming out initially then the window gets fogged or hazed...i was wondering if it is a small leak if the bars leak stuff will or might fix it...thanx...john

brentloftis

Does it smell like antifreeze? You can take a white paper towel orcloth and wipe around the haze seeif it has a greenish tint to it..... but not sure a leaking heater core would cause this, does it also happen on the cold setting? Every time I have had a heater core go out on me I get a puddle of coolant in the passenger side or a puddle on the ground and the smell.

The good news is I think on your 86 the heater core is easy to replace, right behind the glove box and no need to remove the dash butI maybe wrong.

1mustang

it is the heater core.....disconnected and bypassed it and no more fog...also cleared up my overheating problem...did a search and found that some people have had a small leak in the heater core which would allow air to be sucked in thus making the cooling system airbound

mongolchuck

If you have A/C then replacing the heater core is a pain. You do have to remove the dash. If you don't then replacing it is just as brent said.