coolant pressure

[Curtoise]

How pressurized should the pipes be? As the temp sits at a quarter and is stable. Both the tad hoses get very stiff, but I'm not sure what they are supposed to be like ? There not swelling up but it feels a little to stiff

[Pistol Pete]

Can you tell if the coolant is circulating?

[mowgli]

yes, they are meant to be pressurised, and quite hard... the way the cooling system on a nova works means that the rad cap keeps it under pressure, so that as the engine nears 100degC, the water doesn't boil... its all about science... higher pressure, higher boiling point.. the thermostat keeps it running at about 103degC. if you remove the cap, then it drops back to atmospheric pressure & starts to boil up instantly.. to boil up an engine, it needs to be about 125 degC.

[Curtoise]

Thanks for that mate puts my mind at rest as it just stays stiff it it doesn't get stiffer so mist mean its working. Thns

[Pistol Pete]

Same with some other things...if its stiff, its working lol

[Balley]

if it come out the cap its over pressurised !

[Curtoise]

Right my worries might be valid, just went outside and there was a puddle, it was dripping from yhe back somewhere and the top rad hose :( could this be the header tank cap not releasing the pressure when its cooling down ?

[mowgli]

it doesn't release pressure, its a sealed system....

like i said before, if there is a leak, it will lose pressure & boil up..... put it over some cardboard after getting it warm, and check it every couple of minutes to find the leak...

[MK999]

it doesn't release pressure, its a sealed system....

It should do, header cap is regulated to something like 5psi on a Nova iirc, if it goes over that it should hiss out a little pressure to bring it back in line, if it was a perfect seal it would just keep rising until it blew a hose... which is more likely than it forcing a leak really after the rubber hoses have been stuck for however long. Leak is more likely imo, and the cardboard idea is a good one if you don't have a painted garage floor or similar to park it on.

[Curtoise]

I shall try that soon, it feels a awful lot more than 5 psi at the moment

[mowgli]

the manual reckons its more like 15psi....

[MK999]

the manual reckons its more like 15psi....

The 1 obviously wore off my cap then lol

[mowgli]

isn't yours a diesel, and thus it runs cooler

[MK999]

can't say I ever looked closely at that, my header tank experience comes from the 1.6 boiling itself to death consistently shortly after I put it in.

[Curtoise]

Why did it do that ? The temp is now pretty stable around a quater just don't know why its leaking on cooldown rather than when its running.

[mowgli]

cos you don't see it when the engine is running as leakage usually comes out as steam, unless its a proper gusher......but when the engine cools down enough, it comes out as hot water instead.

[Curtoise]

thats most likely right. will tightening them up be sufficient? or shall i take the hoses off and re-seal

[mowgli]

thats most likely right. will tightening them up be sufficient? or shall i take the hoses off and re-seal

only you can decide that one really.... only you can inspect the hoses... most likely one will be shot.. some early 90's gm stuff had a issue with pin prick size holes in coolant hoses...
when i fitted a gsi deep rad into mine, i ended up parts bin checking corsa b ones as the nova ones were either nls or wrong size.

[Curtoise]

Got it on the ramp today and found the leak from the big s shape hose on the back, and top tad hose. Pit better jubikees on them and now its not leaking. But I have just put some cardboard underneath to make sure.

[craig green]

Grease the threads on Jubillee clips, you can then physically get them tighter.

Also as a side note, the pressure seal on the header caps can fail, if in doubt they are easy to replace & free from scrapyards when lodged up your sleeve.

[Curtoise]

haha graig i think i will take your advice, are all the vaux petrol ones rated to release at the same pressure?