[Fot] Coolant conundrum

[Anthony Parker]

I'm having cooling problems.
Need help being convinced that I have to do what I don't want to do.

Brand new short block, same old head, water pump, and radiator.

Over three trials, the engine will run fine and warm up with radiator hoses and radiator warming properly. Then the hoses and radiator will cool and coolant temp will spike to 230+. Radiator cold with sky high coolant temps.

Two more clues, hoses seem to pressurize very quickly and when I opened the radiator cap this morning (after cooling all night) pressurized air and coolant shot everywhere.

No thermostat and I have confirmed three times that system is completely full

Seems I have combustion gases getting into coolant and then bubbles eventually removing pump prime.

Don't know what else it could be.

Given the apparent direction of the leak, is there any use in trying some "stop leak" product?

Is it time to pull the head again to look for warping or gasket leak?

I suppose it could be a cracked cylinder, but this block has been checked by two different trusted engine machinists.

Desperately trying to get to the RunOffs, Anthony.
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