Stiff rad hose

[wannabecummins]

So I had my injectors out awhile back, and when we were putting them in my buddy noticed something. When I started the truck the upper rad hose became pressurized fairly quick. If you try go open the cap it bubbles out. He just did a headgasket and studs on a 05 dodge and when he fired it up it did the same thing. Any thoughts? Leaking headgasket?

 

[wannabecummins]

Bump!!!!!!

 

[TXAustin]

Well... Pressurization does happen when you have a working water pump. Let's think about this:

A closed thermostat (for a cold engine) is going to cause even more pressure in the system. The coolant flows to the top of the ratiator first (hot), right after the water pump and thermostat, which you will see the most pressure. If you're really worried about it change the thermostat, radiator hoses, and radiator cap. If the truck runs well, then let the som-o-b!tch run.

 

[TheBigNasty]

It could just be thermal pressurization. If there is a sufficient antifreeze mixture it shouldn't "bubble", as any good antifreeze has anti foaming agents. Typically crankcase pressure bleeding into the coolant will eventually displace the coolant, resulting in an over full or overflowing overflow tank. Just watch it and note if any coolant comes out or fills the overflow tank. It could be a blown hg or possibly cracked head.