I have a 2004 International with a VT365 motor. The truck has about 108,000 miles on it. The truck overheated while we were driving it on the interstate and blew some of the coolant out through the coolant resovoir cap. Upon closer inspection the coolant resovoir had a 16 psi cap on it instead of the stock 10 psi cap. We replaced the cap and the coolant resovoir (cracked) and it blows coolant out as it is being driven due to pressure in the coolant system.
I'm not sure if this is due to a bad head gasket or EGR cooler. Any ideas?
We've had many EGR coolers go bad but never that symptom. I'm not saying that it can't happen but usually when a cooler goes bad in our buses, they begin to consume antifreeze and then begin to smoke white out the tailpipe. Smoke usually begins when the bus is started. We've never had a head gasket go bad, but I have heard of it several times before. Explore methods to find evidence of combustion in coolant.
If you have a radiator pressure gauge you can attach it and run the engine to see if the pressure jumps as soon as it is started. You can sometimes find a bad head gasket or cracked liner that way. You can also just look for bubbles that start coming out before the engine has even reached a boiling temperature. I have even witnessed the truck not blowing until the engine has expanded with temperature by putting a load on it. Found that one by putting the truck on the dyno and as soon as it was using horsepower the radiator overpressurized as shown on the gauge we had on the radiator. Ofcourse check for oil in the water and water in the oil.
Do it right the first time or do it over when you don't have time.