Ben Jackson wrote:

I found the SCAT tube between the muffler shroud and the defrost vent
in the glareshield has some cracks (you can only see them if you flex
the tube a certain way, which is why they've been missed).

Does this present a carbon monoxide danger?

No.


It's not the heat exchanger
that's cracked, only the tube that carries the warm air to the cabin.
I plan to get it replaced soon but I need to know if I should ground the
plane in the meantime.

No.