My engine died and turns out the coolant had entered the cylinders on the driver side

We pulled out the exhaust and this is what I saw underneath the car...


So we brought the heads to the machine shop and went through pressure tests but showed no leaks whatsoever. We spotted a hairline crack though.



The tech at the machine shop says this tiny crack was the cause of the engine failure. So my question - how is it that the head passed the pressure test but this tiny hairline crack managed to allow water into the chamber? Also, the tech said this head is also bent out of alignment. . . but managed to pass the leak test anyway. Did the gasket allow the water into the system? Am I being lied to?

I need to know what is the root cause of the coolant entering the system, before I put the engine back together. Any advise will be highly appreciated.

I have another question:
I found this "scratch/dent" on the surface of block (this is on the other bank which is not leaking) Should I be concerned about this?



Does it need resurfacing?

TIA

 

Metal expands when hot, hard vacuum can also pull in coolant. If you have coolant in the exhaust, there are not many options!

 

You want to spend the money/time to try to save that head when it leaked once?

 

^if he has a considerable amount of work to the heads then they may be worth saving. If stock then probably not.

 

^They're only polished, ground and got JWT cams + Valve Springs that can be easily transferred onto the other pair of heads which I am getting.

I just needed to confirm if the crack is the only cause and there's nothing else. Gasket seems to be intact. Any other possibilities? And what could have caused this crack? This engine is not even boosted and got only approx 20k miles from my previous rebuild. Never overheated. There's this incident when I did Time Attack event a year ago where the pointer reached "hot" but I stopped immediately (sucks I got DQ'd due to this)

So, basically I'm just double checking with you guys if I am missing anything. I want this 2nd re-build to be flawless.

thanks again for chiming in.

 

could be a weak casting, and hard to tell but that dosnt seem to go all the way through but thats not something we will be able to diagnose online. the instance of it pointing to "hot" could have been a overheat though, normal operating temps for modern engines is over 200 degrees so dosnt take alot to technically be overheating.

 

aluminum always needs resurfacing, you can and wont get it straight or smooth (ra average) wont be consistant and prone to failure, I looks like surface stress, hope after they take .002 - .003 it will disapere, be sure to order thicker headgaskets via what is taken off, cheers