Engin runs fine but It seems that I am getting excessive pressure in my coolant system. My top and bottom hoses felt really tight but not swollen. Only seem to do it after driving for a while. Always seemed fine when at idle. I suspected a blown head gasket. Only problem is no bubbles in filler neck, no white smoke. No oil in the coolant. No coolant in the oil. And did a block test for C02 and came back negative. I did a coolant system pressure pressure a little while back. I think I over pressurize because I had it leak a little bit from the idle air control underneath the intake. Pressure is fine when idle but builds when driving around. Replaced radiator with a new, csf2314. New cap, hoses, and a 190 degree 2 stage thermostat. It did leak once the other day. I couldn't see where from but I suspect it came from the idle air control again. Heard bubbles in the overflow when it happened. The pic above is at idle temp. Gets slightly higher (50% mark) but never higher. Even with the high pressure. is there anything else besides a BHG that can cause high pressure

 

Is your coolant level going down? It may be hard to tell if coolant is escaping through the head / head gasket / block if you have leaks elsewhere.

How do you know that there is too much pressure build up?

The two most likely suspects are the head gasket and the radiator cap. You could also have a crack in the head or block, but the lack of combustion gases in the cooling system seems that a failed head gasket, crack in head, or crack in block may not be likely.

 

Yeah most of us aren't running around with pressure gauges on our coolant systems.

Pressure in the coolant system is regulated by the radiator cap, it's two primary jobs are to let out water after its rated pressure is reached and to allow the coolant back out of the overflow when the system cools off.

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It's not uncommon to find leaks when running a pressure test, some times a loose clamp sometimes a failed hose. It is pretty hard (hard being a relative term) to hurt anything in the engine doing one, unless I dunno you rigged up some contraption involving an unregulated air compressor line.

 

I had a similar situation and thought it was a BHG. Turns out, Every single cylinder in the head was cracked between the valve seats.

 

No coolant loss. The upper and lower hoses are swelling to the point they cant be squeezed very much

 

The hoses are supposed to get more rigid as the system is pressurized. The radiator cap holds the system at a higher pressure to prevent the coolant from boiling into its gaseous state.


Reinforces hoses are not supposed to swell, a swollen hose indicates the reinforcement (cords) have broken and the hose needs replaced because it's a balloon now and not a reinforced hose. Another good sign it's time to replace a reinforced hose is when upon inspection you find the cords are blushing out of the end and or wet.

"Can't be squeezed very much" is not a quantifiable test, the test that needs done is a pressure check on the radiator cap. (Hey radiator cap, how much pressure do you hold before you start venting coolant. Your specification stamped on your body says 13psi, but you're not releasing until 20psi I am going to have to forcably retire you..)