I have now put a thermostat, radiator,clutch fan, new cap and reservoir, pressure tested the system at 15lb for 5 minutes with no fluctuation and a new water pump. I just checked the belt for proper installation and am still occasionally having pressure build up in my system. The truck seems to be running in the normal range during normal driving but still in over pressuring the cap occasionally. It happened 3 times today. doesnt seem to overheat but blows out cap.

Has anyone heard of as problem in which the cylinder walls break down and put pin holes in the cylinder walls creating pressure to build in the coolant system?

I also show no signs of head gasket problems meaning the truck does not smoke at all.

Today I drained the new radiator and put the proper coolant in the system ( I was running water during all of this repair) The system capacity it 32 quarts. Removing the drain plug from the radiator I was only able to put 4 gallons of coolant in before it was full. Could the engine block itself hold 4 gallons of water?

I am at a loss as to what my next step in resolving this issue is.

Thanks for all the info

 

have you boil tested the thermostat and made sure it opens at the right temp?
its easy to do and I have seen bran new thermostats fail. I am still thinking you have a head gasket issue or holes in a cylinder do to no electrolysis control. due to the cylinder pressures exceeding the coolant pressure you will pressure your coolant system up causing loss of coolant. but also the head gasket might be intact enough to hold regular cylinder pressure and only leak in to the coolant system when you turbo is boosting and cylinder pressures are at their peak. if it is a automatic and 4 wheel drive. turn it in to 4 high. or 4x4 high not low. remove the radiator cap start the engine. put it in drive hold the break. give it throttle until the turbo boost comes up and watch the coolant and see if it blows out of the top of the radiator. if it does then you have a head gasket issue. if it doesn't then its something to do with the cooling system.