[M1687]

What type of compound do I use to seal or insulate the heater core as it sits in the case? It looks like originally there was some type of liquid butyl of some sort? (black and sticky)
Can I use silicone? I had someone tell me this is critical.
I've searched all the threads and read the Mustang Monthly article too. :scratchchin

Thanks.

 

[StangLX93]

check out my write on the heater core (heatercore how-to), i used a small amount of silicone, ands it a year later and everything works great

 

[M1687]

Silicone

Did you apply it then let it dry before you put the heater core back in place? Or did you put it on wet and just put it all back together?