rite guys after 4 hours of taking the stupid inlet minifold off to replace 2 little split water hoses at the back of the block :x ive put it all back togethter & bled the water system up. only to notice the water pipe from the rad to thermostat is quite preasurised once the car is warm?? it dousnt over heat & fans kick in as they should & heaters are warm. so just wondering if its normal for the water system to preasurise?? there not bulging its just hard when u try & squeeze it?? :?
preasurised water pipes??
- Thread starter Gaz gtiR
- Start date
jambo_gtir
Member
Id be worried if they weren't hard mate lol. It's perfectly normal for the coolant pipes to go hard. If the pressure gets too much, then the rad cap will open anyway and relieve the pressure.
Being a heating engineer I would suspect this is perfectly normal for a "sealed system" to increase in pressure when it heats up. Water naturally expands when warm. As jambo said I would worry if the pipes were still soft when the system is up to temperature. You only need to worry if the water gets to boiling point ( of which the boiling point increases when under pressure and it lowers when pressure decreases ie when mountaineers boil water thousands of feet above sea level, it boils at alot lower temp than it would at sea level). When water reaches it boiling point that's when you need to worry as the water will boil turn to vapour and in so increases it volume approximately a thousand fold, then it can go nowhere fast enough and pipes go pop! 
hope this helps.
hope this helps.
You asked this already
anyway it sounds to me like you've sorted the leak, well done.There will be a certain amount of pressure, as the temp of the water in the system rises and falls so does the pressure. The max pressure of the system is set by what ever the the rad cap pressure is. The rad cap should stay shut and not release pressure into the expansion tank until that pre set pressure/temp is reached. So if your rad cap is stuffed then this will cause excessive pressure in the system and in turn find weak points in the system susceptible to leaks. If still original, the small hoses on the back of the block are close to 20 years old and famous for springing leaks that are especially hard to see or reach...........
Excessive pressure can also be caused by other factors but we wont go into that just yet
If I were you though, whilst you have access to all the pipework down the back of the block, I'd replace as many of the pipes as possible. You can bet that as soon as you replace everything sods law will dictate you spring another leak