ok so another one of our trucks has the notorious oil in water problem and just kept getting worse so we figurted it was another oil cooler so we got it all torn down and tested the oil cooler with our special testing tool. and it didnt seem to have a leak like the other ones we have tested. is there anywhere else coolant and water could be mixing in the system?

 

the oil cooler is really the only way to get oil in coolant, if it was a head gasket you are more likely to get coolant in the oil. Have you tried putting the cooler in a pot of very hot water and then presure test the oil side to 85 psi, might need the heat to expand it some before she starts leaking.

 

Injector cups??

 

Injector cups usually creates "fuel" in water.