I've got a small amount of coolant coming out of my exhaust when I first
start a stone-cold engine.  The leaking occurs about 20 seconds after I
start the engine.  No white cloud initially.  Also, the coolant temp
guage is about 3mm right of center.  Used to be dead-on center with my
previous 1.9L.

I've got 2 spare working heads in my garage as well as new head
gaskets.  But, I wanted to save these for my rebuild of a different engine.

I also don't want to spend a day swapping the heads if I don't have to.

is there any chance in hell that I can run a ceramic block sealer like
Moroso and seal the head?  I'm not talking about Barrs leak stuff.  I'm
talking about the stuff where you flush the system with water, add the
block sealer, then flush again.   Is there anything that can repair a
hairline leak in a head with the head still in the engine bay?

Or, should I just say "screw it," throw in the towel and swap the heads
out?  Camping season is coming and I plan to travel far and wide with
the family.

Regards,
Craig