boiling coolant help

[coolchris]

hi everyone my cars coolant keeps on boiling up im so confused as to why it keeps on doing it.called AA out he pressure tested system found slight loss traced to 2 loose clips.Tightened then added water and ran system up to temp for 20 mins.temp at 80 to 83 fans cutting in and out no hot spots on radiator air bled from rad everything fine.But things are obviously not fine there are no usual gasket faliure signs(my mechanic told me 100% gasket all ok) car never runs hot no oil/water mix etc.What can be the problem notice also when system is pressured up water comes out of the pressure release section of the tank and drips off the bottom weather the tank is to max or near the min i can understand it doing it when overfilled but not when near the min section.Somebody please help its driving me nuts

cheers Chris

[Metalman]

Hi chris, sorry i couldnt get to see you today mate! I know you recently fitted a new rad on your car and water is obviously in there, but have you checked the thermostat? A sticking thermostat would make the water boil even on a short run, i had one play up on the RX7 and it gave me nightmares, may be worth checking?

Jason.

[coolchris]

hope your feeling better Jason.As you know mate i dont know 2 much about cars but wood it affect the weather the fans cut in or not with a faulty thermostat.This problem is driving me crazy mate

[Urbalizer]

Ok the system was pressure checked and then the pressure leaks were found and fixed.
Only one thing missing from that pressure check was the pressure cap, seems it needs replacing, if you steam being released from uder the coolant header tank this is the pressure cap that has gone.

[Gadgeroonie]

you may need to bleed the system if you had lost some fluid

could be air bubbles trapped in the system

it could also be a head gasket - is it a 2.5 or a 3.0

[Urbalizer]

coolchris said:

water comes out of the pressure release section of the tank and drips off the bottom

cheers Chris

This is a clue that the pressure cap has gone, or the thermostat might be not be opening, if you replace the pressure cap and it still does it i would look at the thermostat, Like you said the head gasket has been checked so we can rule this out.
I think it is one or the other, assuming that the pressure check on the system was done correctly, there is also a chance that more leaks have sprung up since the pressure check, once the hoses have gone, then just tightening the clips cures the problem temporarily, because they cut through the pipe and make the leak worse.

Get hold of your pipe taht goes to the aluminium tee junction below the coolnat tank, and bend it, if it splits you need the hoses replacing.

[JLSELAN]

coolchris said:

hi everyone my cars coolant keeps on boiling up im so confused as to why it keeps on doing it.called AA out he pressure tested system found slight loss traced to 2 loose clips.Tightened then added water and ran system up to temp for 20 mins.temp at 80 to 83 fans cutting in and out no hot spots on radiator air bled from rad everything fine.But things are obviously not fine there are no usual gasket faliure signs(my mechanic told me 100% gasket all ok) car never runs hot no oil/water mix etc.What can be the problem notice also when system is pressured up water comes out of the pressure release section of the tank and drips off the bottom weather the tank is to max or near the min i can understand it doing it when overfilled but not when near the min section.Somebody please help its driving me nuts

cheers Chris

Might compare with similar discussion here:
http://www.nobleforums.com/showthread.php?t=1276&a...

Note post #6, for example, where Paul C. points to localized boiling as a common occurrence, which can be traced to the extreme heat soaked into the turbo cooling jacket that persists after shut down.

[coolchris]

Its def not cap as replaced with new one other day thermostat hopefully is problem going to put a new one in and see if that cures it

[Urbalizer]

coolchris said:

Its def not cap as replaced with new one other day thermostat hopefully is problem going to put a new one in and see if that cures it

If thermostat is ok, i would seiously condider pressure checking your system again, if the system is losing pressure again and leaks spring up the only cure is to replace your hoses, also the ones going to the turbos.

[mgbond]

So am I better off buying pre mixed, if so what type and how much as I need to completely replace mine.

Thanks

Bondy

Just been checking and it looks like pre-mixed is a rip off. So what brand shall I get and how many ltrs does the Noble hold?

Bondy

Edited by mgbond on Monday 26th October 19:01

[coolchris]

tested thermostat in saucpan of water when water started to boil it opened so really confused now

[Urbalizer]

Pressure test the system again, have you had new hoses? When the guy tightened up the hose clips last time, they may have cut through the brittle rubber and made the problem worse.
Have you tested the pipes yet, roughly under the coolant tank to the right, you will see an aluminium tee piece, take the pipe to the left and disconnect it, bend it on itself, if it splits you have found your problem, the hoses need replacing.