cooling system problem

[marc69]

My 1.3 Sr seems to have a cooling system problem. When I bought it 6 years ago the header tank was split at the top. I put on a new one but never did any 500 mile journeys till now.
There was water leaking from the jubilee clip failing on the bottom radiator hose last
week which I replaced. now looking at coolant levels there seems to be a few problems.
there is always. been a water noise inside the car.
the coolant level is dropping slightly when the engine is hot
this header tank looks like it is about to split
occasionally the car is pumping out smoke, might not be related?
it looks to me as though the system is over pressuring but there is no oil and water mix
but I am worried about blowing head or gaskets if it is stretching the header tank.

I am thinking the drive home should be done with the wee pipe at the top of the header loosened?

any advice please?

[brainsnova]

Could be an air in the system causing excess pressure or possibly the matrix is choked up giving you the water sound

[millworm]

Deffo sounds like an air lock, the coolant will drop slightly when hot but should return to normal when cold. what colour is the smoke? white? if so is it only on start up or is it after it's got hot and been running for a while? if the header tank looks like its about to split maybe the the cap is failing and not releasing excess pressure.

[deneil_gsi2000]

Check it has the correct cap on the expansion tank, it should release pressure at around a bar. So if 5he tank looks like its about pop then the cap is definatly not right

[meritlover]

as above, it sounds like an air lock.

try topping up the water with the front of the car slightly elevated and passangers side a wee bit higher. this will encourage any air to rise to the header tank.

the cooling system is designed to run at pressure to stop the water boiling off, if you disconnect a hose to drive home, you will just loose even more water through it either pumping out or boiling off.

do a full bleed, check and replace any suspect hoses to remove any doubt about leaks before jumping to conclusions about head gasket failure.

even if the gasket has failed, its really not difficult or expensive to change.
the cap is designed to 'blow off' on over pressure anyway so you arent really gaining much. A hose will let go before the header tank does, unless its in hideous brittle condition.

whether its a 500 or a 50 mile journey, that wont make much odds as once the system is up to pressure and engine is up to temp it is self regulating.

remember that the cylinder pressure is higher (about 170psi) than the water pressure (about 15psi) so the gasket failing is more likely to blow the cooling system than the other way round.

[mowgli]

the temp sender on the manifold is also the bleed point. you must also have the heater valve on hot.

it was a very common thing back in the day.. if you bleed it right thru, having pumped all the big hoses to make sure, and then after driving any distance, you find it does it again, then its the head gasket.

buy new bolts & a gasket. unless the surface is pitted, just clean up the surfaces & reassemble.

[meritlover]

i didnt remember nova heaters having valves, i seem to think there were dampers that shut off the flow across the matrix.

the heater circuit is open all the time as its the main bypass circuit for the water pump to allow circulation whilst the main thermostat is closed.

[marc69]

Well I got home!

Thanks for the advice so far, I didn't release the pipe but I removed the rubber seal from the cap so it wouldn't seal 100%. When squeezed yesterday the hoses were completely rigid and unsqueezable, today with the cap seal removed, they were a bit softer.

I have driven 500 miles and the level is still the same although it is hot at the moment, I expect it to fall a little when it cools down. Driving down on Sunday, I went through nearly 3 litres but this may have been a combination of high pressure with the cap failing and the jubilee clip weakening, small water drops getting out and over a long journey...

Yesterday there was two or three occasions of blue smoke on acceleration when it was hot but none at all today, perhaps I was looking for faults?

The matrix has been noisey for at least 6 years (since I got it) but the heater gives a great heat when hot, so it does work. If the water level in genral has maintained this journey, is it perhaps just an air lock in the matrix making the noise and the header cap that is at fault? Or is it more likely to be cylinder gasket?

If it is gasket, why is it causing excess pressure (rememebring the car came with a cracked open header tank and yesterday there were signs of stress on the one that's on now)?

[meritlover]

iam happy you and your nova got home.

These cooling systems are very simple and very rarely cause problems with air locks. Now you are home you can replace the rubber seal and check over everything, give it a thorough bleed and do shorter more confident runs.

it the pressure comes from the cylinders pressurising the water jacket and therefor blowing up your hoses and header tank due to the gasket failure and the communication between the two systems.

it is unlikely the header tank is 'at fault'. Normally a 15 year old hose would rupture before a header tank if its being pressurised to that extent.

if you need help with changing the gasket i can talk you through it and hold your hand.

£30 max if you do it yourself.

[mowgli]

if it is gasket, why is it causing excess pressure (rememebring the car came with a cracked open header tank and yesterday there were signs of stress on the one that's on now)?

the head gasket on an ohc nova can have a habit of leaking, as opposed to blowing. It can pressurise the coolant & not contaminate the oil. When the ohc small block was launched, gm actually used lower torque figures in their service info. This got updated after a few years, as the gaskets were leaking, then people were fitting new ones at the low torque figure. The gasket would then last about 9 months & go again....also people weren't used to changing head bolts in those days... They finally upped the torque & advised fitment of new bolts. ( i got thru a lot of gaskets in my 1st nova before finding that one out.)

the cooling system on a nova is pressurised. Thus the system runs at a higher pressure inside.. Because of clever science, this allows the coolant to run at a higher temperature without boiling. If the expn tank was leaking, or the rad cap was knackered, then it would lower the boiling point of the coolant, and add to airlocking & overheating problems.. This can then cause the head to overheat, and damage the gasket.

[mowgli]

i didnt remember nova heaters having valves, i seem to think there were dampers that shut off the flow across the matrix.

The heater circuit is open all the time as its the main bypass circuit for the water pump to allow circulation whilst the main thermostat is closed.

sorry if i used the word valve as a description, as i've never had one out of a nova & examined it. But the point of having the heater on hot is to ensure that there is no trapped air anywhere in the system

[meritlover]

no, i mean there is nothing that restricts the water flow in any way. so the matrix has full water flow at regardless of heater setting. Therefor having the heater on will do nothing to help bleeding.

[mowgli]

oh. i see. ok, thats something else i learnt today. i've always set heaters to full when filling cooling systems to ensure there is no chance of airlocks.. i didn't realise they cut the air feed off..

[marc69]

Thanks for the advice so far. I took the header cap off my swing and put it on the SR yesterday I emptied the cooling system and slowly refilled it. The water was a perfect light Blue with no sign of corrosion anywhere but I suppose most of it had been replaced during the last week! Then left it running till the fan came on.

Today i drove just over 30 miles and now having left the car sitting for 4 hours the water level has not moved at all. I also noticed that when it was hot, the big pipe to the radiator was firm but not as before..completely rigid.

Wouold you agree that it looks like the cap must have been failing and perhaps there was an air lock? I assume if it does start loosing water again then it has to be the head gasket.

The heater matrix is still noisey though? It has always been like this and perhaps I will just have to carry on living with the running water noise.

[meritlover]

as long as its not loosing water or over heating it's fine.

if the matrix bubbling is annoying, turn the radio up.

[marc69]

as long as its not loosing water or over heating it's fine.

if the matrix bubbling is annoying, turn the radio up.

Thanks and the last bit made me laugh out loud (rather than lol)

[meritlover]

iam glad, have a nice weekend. :)

[marc69]

iam glad, have a nice weekend. :)

you too

[marc69]

Now after running the car for a few weeks and having sorted out all the other problems at last. It is still leaking a little water somewhere so i suppose it has to be the head gasket. There is no water oil mix.

Some advice please as I intend on doing it next weekend.

1. Gasket, do I need new gaskets for the inlet/exhaust etc or am I ok with just a head gasket? (I will get new head bolts)

2. I assume I just follow the Haynes guide faithfully?

3. If I drain the water system completely do I need to drain the oil and fill with new oil? I just did an oil change a few weeks ago.

4. Once done can the car be revved fairly hard almost immediately or does it need a few miles etc to settle in?

Whilst I don't mind paying for essential parts, i have spent a small fortune lately so just want to buy what is necessary.

Thanks

[therealnovaboy]

1. You should get away with keeping the inlet and exhaust manifolds on the head (unless its a four branch manifold) and lifting it off as a oner. if you do this you split the exhaust down pipe from the manifold so may need a gasket for that. remember and get bolts. dont reuse them

2. Yes. watch what haynes you use for torque settings as I think the early one is wrong.

3. you shouldnt need to unless you find the water has been getting in the oil. just drain the water before you start. if it looks fairly clean you can re use it. remember there will be some oil in the head so dont go throwing it around/ turning it upside down and youll be ok.

4. once its up to temp, youve checked for leaks, and checked fluid levels you can do your worst.

Consider the milage your timing belt has done as it may be worth firing a new one on. Dont cheap out on a gasket use a gm or FAI. Also the FAI bolts still have the hex heads, which is nice.

[marc69]

Thanks, I have a belt ready for it anyway as the original is 7 years old, held off fitting it to see if I need to take the head of first.

Has to be hex bolts, can't be doing with this star stuff lol

[mowgli]

hex bolts look right on an old 8v. haynes is definitely your friend for this one, but make sure you have the later light blue one with the 1600 engine stuff listed.. it has the right figures.

[marc69]

hex bolts look right on an old 8v. haynes is definitely your friend for this one, but make sure you have the later light blue one with the 1600 engine stuff listed.. it has the right figures.

Thanks, I have the green book which I think is a later one too, it has the revisions bit at the end, I'll see if the torque settings there are different to section one.

[mowgli]

the figures will be right in the green one, i just don't like the dumbing down they did to it

[marc69]

I changed the gasket today, massive job! I took it for a run round the block but it will probably take a few weeks running to tell if that is the problem solved. Here is the old gasket, is there anything that leaps out? I didn't notice and cracks etc, but i have never seen a failing gasket.
http://i988.photobucket.com/albums/af5/69marc/Photo528_zpsc40f0c31.jpg
Also the new is is FAI, it doesn't say OBEN but has a Z (or N at 90 degrees) whoch I assumed was the same marker.

[meritlover]

its always hard to tell, but the discolouration of the firing ring between cyl no.1 and the water jacket looks suspicious and would give the symptoms you had before.

OBEN means top and should be fitted with that facing upmost. The oil holes to the head wont line up otherwise.

[marc69]

Thanks, hopefully that's the water problem sorted. Will take a few weeks to see, as sometimes before it would go two weeks and not loose a drop, the next day lots!

The new gasket didn't have oben written on it but, I lined it up so it sat as the old one did (holes etc) and have just driven 40 miles so if oil wasn't reaching the head, I assume my tappets etc would be noisey?

[meritlover]

The new gasket didn't have oben written on it but, I lined it up so it sat as the old one did (holes etc) and have just driven 40 miles so if oil wasn't reaching the head.....

....you would have known by now. Sounds fine,

Good work!

[marc69]

Thanks