was changing fuel filter last night in my 96 7.3 , notice the top rad hose was very hard when the truck was running , also noticed the degas bottle had like an oily film in it and it had a lot of pressure when I removed the cap , would the pressure build up be a bad head gasket or a leaking injector cup or cups?? truck has about 360000 km showing. has recently had new waterpump and thermostat, never noticed anyoil or fuel in antifreeze when replacing them.

 

Most likely an injector cup ...

 

Thanks hope thats what it is

 

2x for the injector cups. Fuel in the coolant is the classic symptom of a bad injector cup. Just to be sure you know too, you can rent the tools needed to change them if you would rather not buy them. I think it is Rosewood Diesel that will rent you the tool kit. And they can be changed with the engine in the truck.