Upper radiator hose is firm

[LFY]

Loss of power, overheating, toothpaste in the oil, misfiring.......

As I said earlier, my car has non of these symptoms and runs fine. The engine has so much pulling power and to make sure about it's power i had a drag race with another car of the same kind and i won! I love my car and that's why I was worried about the hose and wanted to make sure it is not dangerous to drive the car in that condition.

[Stickyfinger]

make sure it is not dangerous to drive the car in that condition. ?

Stop worrying
As others have said....it is in good condition and quite normal.

[Harlequin]

so if an engine is none of the above - but undoing the cap on a hot engine results in both pressure and a gush of water?

[elma]

No, the cooling system is under pressure when hot. Taking the cap off releases the pressure so the water expands and vapourizes (possibly).

[white exec]

...and could cause the coolant to immediately boil, as the pressure is dropped, and the boiling point drops.
It's for that reason that User's Manual advice is always to remove the cap on a hot engine only with precautions and extreme care, or not at all. The water in an overheated engine could be 30degC above normal 100C B.P.

[Hell Razor5543]

I was reading somewhere that the water near an underwater volcano can easily exceed 500C, but (as the pressure is too great) it cannot actually boil (turn to steam).

[Stickyfinger]

It is also hard to have a good hot cup of "cha" in the Himalayas, one reason for "Sweet Tea"

[elma]

I can verify that tea in the Himalayas leaves a lot to be desired. Weak green tea is my choice out there but still isn't great.

[Hell Razor5543]

I remember reading an Arthur C Clarke book "A Fall of Moondust" when a tourist dust cruiser 'Selene' was out at work when a quake caused a Lunar cavern to collapse, and the 'Selene' fell into the resulting 'whirlpool' and went under the dust. The Captain (Pat Harris), in order to try and improve their chances of rescue, increased the air pressure to around 1 BAR. Later on one of the passengers made a comment to Sue Wilkins, chief stewardess, (after drinks had been served) along the lines of "I say, Miss, this is a really nice cup of tea, the best I have tasted on the Moon", not knowing (although somebody else did) that in raising the air pressure the water had boiled at 100C (as opposed to the normal 80C), and so the tea had brewed properly.

[myglaren]

Read the book but didn't remember that James.

[Hell Razor5543]

It was only a throw away line, mainly (I think) to allow for the introduction of an experienced space voyager to make himself known to the Captain, but in such a way as to allow said Captain to know he had useful support, should he require it.

Found it.

'Then, cutting across the low murmur of conversation, they heard a very English voice call out: "I say, Miss - this is the first decent cup of tea I've drunk on the Moon. I thought nobody here could make it; my congratulations".'.

A few paragraphs earlier, after realising the hull was under great pressure, Pat slowly turned up the internal pressure by 20%. When it had stabilised, an elderly gentleman said "I think that was a very good idea". It turns out this gentleman was Commodore Hansteen, under an alias of Hanson (so he would not get recognised and could go sightseeing).

I have a very battered (worse than foxed, more like badgered, beared, and (possibly) lioned as well) Arthur C Clarke book, making up '2001: A Space Odyssey', 'The City and the Stars', 'The Deep Range', 'A Fall of Moondust' and 'Rendezvous with Rama'.

[LFY]

You are all right. But there is something I don't understand. Why Peugeot has chosen such a high pressure radiator cap for a normal passenger car?

Peugeot 406 1.8 is not a high performance car like a Ferrari or Porsche!

Most cars use around 13 PSi pressure caps. Even a 10 PSi pressure cap can still increase boiling point to the extent higher than needed in a passenger car.

1.4 bar = 20.3 PSi! That's extremely high for a 406 1.8!

The boiling point of my car's coolant = 110 °C

Can someone please explain the reason behind using a high pressure cap for a city car like 406?

[white exec]

Even a small engine can wind the water temperature up considerably; a lot depends on the size of the radiator, whether auto or manual, petrol or diesel, AC or not, etc. 1.3 or 1.4 bar is pretty common, these days.