I tried the search but nothing fit my problem quite right.
2000 Jeep xj with the 4.0. Belongs to son. It shut down on him and I picked it up to fix. When cold starts right up and was pushing bubbles out of radiator with cap off. As it starts to warm it violently blows coolant out. So head gasket or the known head crack issue.

Replaced head with a TUPY and did head gasket. New everything, gaskets, bolts, etc. Just put it back together and it is still pressurizing the coolant system. Starts off with just small bubbles coming out of coolant with the cap off. after just a few minutes warming up it is violently blowing coolant out in gushes every several seconds. After I shut it down I could hear bubbles going from the motor towards the radiator through the lower hose. Runs smooth but coolant and combustion chamber is meeting somewhere I believe.

Entire cooling system is new. Replaced everything 3 months ago. rad, fans, pump, temp sensor, thermostat, fan clutch, everything.
I know it points to head or head gasket but being that I just replaced them I'm not sure where to look. What are the chances of a crack in the block?

 

try pressurising your cooling system

if you lack access to the correct toolkit, a bike pump and inner tube can be clamped over rad neck

listen if you can find out where the leak is coming from

I would perform a compression test

neither of these tests are definitive, but may give you a clue

 

For a crack in the block to be blowing bubbles, you probably would have noticed cracks in the cylinder walls.

 

coolant pressure tester on the way. as far as cracks in the cylinder, I didn't really look to hard. gave a quick look but because I found the crack in the head in the expected spot I didn't search to far beyond that. Just a cursory glance to check for cylinder wall scoring of which I didn't see any.

 

did you do a compression check?

logically, the most likely point of failure for a piece of machinery that has just been worked on, is, unfortunately, what just got "fixed"

therefore, I would certainly do a compression test, probably show up head gasket or similar issue, not very time consuming to try

(I usually try to perform one prior to dismantling any engine with suspect parameters)

 

Not yet, my compression tester is loaned out. Waiting on next days off to do more. Guess I could use cylinder leak down tester instead to see where air pressure goes. Coolant pressure tester is in. Will update on day off.