C15 cat bubbles and pressure radiator

Immediate cooling system pressurizing on engine start. Blows coolant out of the radiator cap. Apparently engine lost coolant last year and was overheated. driver filled it with drinking water asap and kept going. Put a cooling system tester on it to check for exhaust gasses and it changed colors.

Just pulled the head. All 6 cylinders exhaust valves cracked between valves. Possible head gasket blown as well. Looking for input on this. Not really sure what I'm looking at or checking for.

 

no possible about it head gasket is blown

 

What about the cracks between exhaust valves? Showed photo to service manager and he said definitely head job? What should I be looking for on the sleeves, block and spacer plate. Nothing looks obviously damaged. Was looking for a break in the fire ring but I guess that isn't a necessity .

 

Liner protrusion is very important. Also if it has not had anything in it other than water for a long period of time you may have pits in your liners.

 

More than likely your looking at a infame you gotta find out what your liner protrusion is before you just slap a head back on it

 

I'll print up a worksheet and go thru the numbers on it to see where we are at on liner protrusion.

 

there is a thinner spacer plate if your not to low

 

Little bit better photo and it becomes a lot clearer.
On the rest of the cylinder fire rings you can see the gray gasket material forming a raised circle except between #4 and #5 cylinders where #4 blew out. Would anything else cause that but bad liner protrusion? Had 2 head bolts a bit on the rusty side between #5 and #6 cylinder on the passenger side.

 

Zoom, zoom, zoom and there she is. The obvious...
So, what's the best way to clean a block with the liners still in? Just scrape everything into the coolant passages and slap it together before anyone notices? any tips appreciated

 

Do everything you can to get all the trash to the outside of the engine. Heavy abrasive discs can get particales similar to sand in the crankcase. That can damage a lot of stuff.
I have worked for some of the cheapest of cheap ##### at times. Experience is educational. If the head was hot enough to crack like that the liner O rings were most likely overheated a well.
At a minimum pull the liners. Inspect them. If OK hone them and reinstall with new O rings. That is provided the pistons are in good condition. Do the ring lands check OK with a gauge?
Replace the rings as you have them out but also because they may have lost tension.
When you price all the individual parts you can probably buy a good aftermarket overhaul kit for less.
Measure liner height before you take it apart. If it is wrong now new parts is not going to fix that.