blown head gasket or egr cooler??

2009 peterbilt 387. Isx cummins 719,000 miles

Friday night I shut her off while I went inside truck stop.
I was in there about 20 minutes. I went to leave started the truck she had a bad miss running on 5 cylinders for about 15 seconds. White smoke so bad that it filled the parking lot.
I took it to a shop they put a tester on the coolant reservoir with a purple liquid that very quickly turned yellow. Not to mention the motor hydro locked after sitting a couple hours. That was Saturday morning. . They say head gasket possible that the head is junk too.. so we talked about a complete inframe. They couldn't start on it till today.. they called to tell me they now think it's only a egr cooler... I know the truck will burn antifreeze but I've never heard of hydro locking and having exaughst in the coolant reservoir from a bad egr cooler.

 

Same here I've never heard that on a "big truck". The mechanic is going to pull the cooler and the egr valve and inspect them then call me back... that test they did on Saturday was a combustion detection test wich it failed instantly. . I'm not getting my hopes up on this I've come to accept a complete rebuild. . What sucks is I just bought the truck haven't had it long enough to make a payment yet.

 

I'm familiar with the bubbles test.. but that egr cooler or the egr valve itself wouldn't put combustion gasses into the coolant reservoir would it??

 

They called me back and said head gasket possible that the head is junk too. . So.... I guess it's best at 720,000 miles just to go ahead with an in frame. . Oh well at least now I'll have a fresh motor with some warranty on it. I owe I owe it's off to the shop I go

 

They pulled the head today.. no sign of the gasket blown.. I don't know if they even took a good look at the egr valve or not.. they are so sure that it was the head gasket but now they say could be the head...