Aftermarket heater core issues

Ok, well i procrastinated on this long enough and finally have heat.

After swapping in the OEM core from Steve at 300zxpartsforyou and getting no heat, i said fuck it and stopped working on it.
I figured that i must have a clog in the return line somewhere before the thermostat, that must have been from a blue shop
towel used to plug the hose when i pulled the heater core. I resigned myself to having to pull the waterpump and thermostat
housing to find the clog. .....but i don't remember using any shop towels....

In my procastinating I did other things like tracking down various cabin water leaks and rust treatment under the seats from said leaks.

I also helped my neighbor sort the hacked stereo harness and get the aftermarket deck working in his 86Z.

Then i helped my other neighbor install a catalytic converter in his 97 Accord, which brings us to my heater core…

I happened across a youtuber that puts out car repair videos, ericthecarguy.com when researching catalytic converter cleaning
methods for my neighbors accord. I started watching other videos and found this:



MFW


Fast forward to tonight and 34.99 at Napa



I disconnected the electric radiator fan and installed the funnel with the parts included.
After i started the motor and shimmed the throttlebody to keep the rpms ~1500, I saw
a somewhat steady burping of bubbles coming out as the engine warmed up.

After about 7-10 minutes i could tell the defroster was getting warmer than it had in the past.
I let the motor run until i could verify with my borrowed FLIR cam that the thermostat was open



(Eric uses a FLIR cam to do just this in one of his tool reviews about a FLIR camera,)

Again,


After the thermostat opened, the heater really kicked in, this is a shot of the duct behind the digi cluster (cluster is out)





I never suspected air because I've had the heater box out a few times in the past to fix leaky actuators and never had a issue,
but the difference this time i guess is that the heater core was dry when installed and had air trapped in
it, not enough coolant was circulating through it in the closed system for it to burp out. Only after running it in an open
system, which the Lisle 24610 funnel (Napa SER774000) allows you to do, allowed it to be burped.



I'm sure that tra[[ed air was the problem with the aftermarket core, but i don't think i'll use it unless i have too.
If only because it is a poor fit and had to be shimmed/secured with foam insulation to seal around it.


tl;dr air was trapped in the heater core, used an overpriced funnel to burp the cooling system.

Case closed.

I use the Matco version of that on everything that I do work on that touches coolant. Used that on my Z when I got the engine together and burped the air out so fast. Such a handy tool and keeps spillage to a minimum.