91 civic - tough question about cooling
 

first i'd like to say thanks to the great people on this forum for all
the help they provide.

i've done a search for my problem and i've found some things but
nothing exactly fits.

i recently performed a head gasket job on my civic. i began this job
because i had bubbling in my coolant resevoir after driving for a
while. i also had some electrical issues, but i don't see those as
related to the bubbles. the bubbling was not boiling. some kind of
gas was pushing through to the resevoir, and i assumed it was
compressed gases of some kind coming from the cyclinders through the
head gasket.

after removing the head, i took it to the shop. they told me the head
had to be machined by 6 thousands to remove the warp, which seems like
quite a bit. he also pointed out where the likely breaches of the old
gasket were.

i cleaned and lapped the surface of the block. there was no apparent
cracking or warping (i checked for warp with a quality straight edge in
multiple directions).

put everything back together to spec.

i filled up the cooling system, on an incline with the radiator high.
bled the system according to haynes.

i've been test driving it for several days, and what happens is a
little weird. after a light drive, i get a few minutes of bubbles
(again, not boiling - bubbles) and i can hear coolant sucking past the
rad cap in pulses. after a heavy drive i get the coolant pulsing, but
much more bubbling - like the bubbling i used to get.

the only thing i have found that i didn't do was crank on the heater
when i was filling the cooling system. is it possible that since i did
not do this, there was a chunk of air in the heater core that is now
escaping when the car heats up? i ran the car tonight at idle with the
heater on full blast after discovering this possibility, but the rad
stayed full (again on an incline) even with the bleeder open.

it seems there are three or four possibilities:
1 - block is cracked
2 - head is cracked and crack missed by shop
3 - heater core had air bubble and now air is working out
4 - head gasket was installed improperly

any thoughts? thanks.