wont start no matter what new batteries and glow plugs while replacing plugs found coolant in number 8

 

start with checking the cranking rail pressure they take +-1400psi to start. if you have that and it wont start check compression in all 8 cylinders it should be 400psi or more.

also do a pressure test on the coolant system it it sounds like you have blown headgaskets on top of your no start problem

 

thanks man i knew it was probably HG but wondered why it didnt start

 

i'm gonna guess that your injector return rate is too high and that is causing the low rail pressure which is causing the no start condition

then if the coolant pressure rises over 17psi or so then you for sure have a head gasket blown but also it could just be the injector cup on the #8 cylinder also