Normal pressure cooling system m50b25

[4dri4n]

I'm sure it has been asked before, but it seemed a bit dificult for me to find a definitive answer, so I wanted to ask anyway if you don't mind.
What is the normal operating pressure on the coolant system?
My car gets a bit of pressure but I don't know if it is normal or maybe there's a small leak from HG. It is an m50b25 engine.
Bentley manual states that the cooling system is pressurized.
But when I start the engine it builds up pressure relatively quick. Maybe it takes just like 5 to 10 min of normal driving to reach some pressure. Even when the hose up top from radiator is not at its normal temperature, (hot, but you can touch it) it starts to have some pressure.
There is no water consumption, and no problems with the coolant cap releasing anything.
It is just that when I press the hose with my two fingers I can't join them; no way.

[whiskychaser]

Rad cap is rated at 2.0 bar. Confirm by putting entering your VIN at realoem

[4dri4n]

Yeah I know that, but that pressure would be under abnormal operating conditions such as overheating or HG failure.
The thing is that many people told me that is not normal to have such a pressure that you are unable to depress the hose with your fingers.
What I would like to know is what is considered "normal".

[whiskychaser]

Your top hose may have hardened through age but I still think it is normal. The hose is full of coolant at around 20 psi. You are doing well if you can compress that with your finger and thumb. Try compressing a plastic Coke bottle which is half full. Easy with no top on it. A little different with the top on :-)

[nonturbodan]

If you have a head gasket failure the system will over pressurize until something lets go. Combustion gases would pressurize the system to several hundred PSI if it would hold it. Either the cap will blow off, a hose will burst or the radiator or heater core will blow up. If it has not spit anything up I would not worry about it. It'll definitely let you know if there's a problem.

Another sign of head gasket failure is residual pressure building up in the system after the engine has cooled down completely. If you have significant pressure left over after the engine has sat for a day or two, that would be abnormal since the only pressure in the cooling system should be that which is generated by thermal expansion.

[4dri4n]

What really makes hard to understand the cooling system for me, is that, how is it possible it gets pressurized given the fact that the thermostat is rated to 91 degrees? The coolant mixture has the boiling point at 120 degrees or so, so to build up pressure in there, there must be somewhere in the engine where that temperature is reached and therefore the hoses become hard as a result from that boiling. If there is no boiling, there should be no pressure.
Bentley manual however states that is a pressurized system and well it must be I guess! But I dont know how unless there are some hot spots on the head wich increase the pressure high enough...

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The thing is that, a friend has an e46 m3 wich has in some way, a similar engine. Iron block and well, six inline and so... aaand, it gets no pressure! Whats the difference between the s54b32 in terms of cooling and the m50? What makes the m3 e46 engine cooling so it does not build up pressure or hot spots or whatever?
However a 328i e46 of a friend does even get more pressure than mine does! Coolant hoses get crazy hard!
I dont know... If I had to design a cooling systme I dont see the point in making them pressurized... unless I wanted to raise the boiling point of course... and If I had to do so, I would never design it with plastic parts... instead, the thing should be lowering the temperature even more I guess so it doesnt gets any pressure.