'88 Vert BONE stock
I put a motor in it and pulled a radiator from a junk yard. I flushed EVERYTHING before it was ever started.

The system is building a lot of pressure and the cap is releasing pressure into the overflow tank but its all just air bubbles. It doesn't fill the tank up with coolant. The lines running to the cold start system and BACV don't get warm unless you rev the motor. Radiator gets "hot" but i can still hold my hand on it without getting hurt.
Now before you call me stupid. I have bled the air 4 (yes four) times now.
Checked the oil and it is coolant free.
Smelled the oil cap and it just smells like fuel and oil (normal)
No smoke out the exhaust.

This is happen at idle. I have not and will not drive the car under these conditions.

Also may be and unrelated problem but the temp gauge only reads a hair above the cold line. Then will randomly spike up to half way. If i shut the car off and start it again it reads cold again.

 

Have you pressure checked your coolant system? I think pineapple racing sells something of the sort to see if it's holding pressure. I'd also start with a compression check as well. My last N/A S4 blew a seal before it ever started smoking; eventually realized it was leaking slowly enough for bubbles in several places...

 

It does sound like a combination of huge air bubbles and a sticky thermostat. Or, a water pump where the blades have rotted away.

You're going to need to do a bit of troubleshooting here.

First, to eliminate the possibility of a bad coolant o-ring, perform the bubble test. With the engine dead cold, remove the coolant filler cap. Start the car. Do you see a steady stream of bubbles from inside the engine? Rev the engine using the throttle body. Do the bubbles increase significantly? If so, then you are probably looking at a failed coolant o-ring or a cracked iron (S4 issue mostly).

That will give you an indication if you should continue. A cooling system pressure test is better and will find all the other leaks probably present. You can rent a tester at an auto parts store.

If you don't have any internal or external leaks, you need to pull the water pump and thermostat and check them.

Are you sure the junkyard rad isn't clogged?

 

Junk yard rad was flowing perfectly with a garden hose in either end.
Did the bubble test and didnt see anything bubbling out of the filler. The fluid just stayed even with the top of the filler. Although i didnt try revving it up with the cap off.
I do think i found a small leak coming from the cold start mechanism on the TB. I'll be checking into that when the car is around again.

 

The garden hose doesn't mean anything. 3/4 of the tubes could be clogged and the hose would flow fine.

 

Ok after checking again and again and again.... it turns out that it really is a bad water seal. Its very obvious now. Lots of bubbles.

Almost had the damn thing sold too!!

Anyone know what an excellent condition 88 vert would sell for with bad water seal?