How to check if the liners are bad on a detroit 60 series

I had oil in my coolant on my freightliner Columbia. turned out to be a bad tranny cooler.

are you using engine oil?

I second the multiple flush. it took 3 dish soap and water flushes to clean out mine and it still wasn't 100%

 

Which engine you had replaced cooler sir

 

Having a issue with my 60 series Detroit 12.7.. Bought truck from a Guy, have paperwork on the head been reworked back in Fed 2020.. Any-who the coolant is going somewhere.. Pressure test was done @ machine shop and done by my mechanic.. No leaks, no coolant in the oil pan nor oil is in my coolant.. Any idea what it could be, being the head been reworked by Commercial Fleet..

 

Check transmission if you have a transmission oil to engine coolant transmission cooler.