as posted on general, STi4 typeR, using about 1/4 pt a day, but seems to be losing it out of the rad headertank (blowing back?)is this a common trait with a headgasket thats blown, i.e pressurising the water system & blowing it out of the headertank (new rad cap fitted)

TIA
Andy

 

You should also notice it goes a milky brown colour too.....Then definately head gasket has gone but is it 1 or 2?

 

My mate is filling up the aluminum water header instead of the plastic header tank, he noticed that after a run it was only half full & the plastic header tank was reading the correct level,

it seems to be refusing to draw extra water from the plastic header, so he tops up the aluminum 1, next day halfs gone again but the plastic header is showing the correct level, when removing the aluminum header tank what level would you expect the coolant to be sat at when cold

Edited to say his water in the platic header is pretty clear not oily brown

TIA
Andy

[Edited by Andy McCord - 6/24/2003 11:55:13 AM]

 

Andy

The aluminium tank will always be lower after a run. The water in the system will expand considerably when its hot. Th water is normally between 85dgeC and 98degC at the point where its measured (the head cross over rail) but can exceed boiling point around the cylinder liners. The steam bubbles will cause some of the water to be pressed passed the cap and into the overflow.

If you monitor the water level two days later, you should find that it has not moved from this lower level, which is normally about an inch down from the cap. The volume of water that you have lost is about half a cup full, out of 7.5 litres.

If the level keeps going down, it needs closer investigation.

If the head gasket has failed, the escaping pressurised cylinder charge will leak to the coolant void around the cylinder and will push substantial amounts of out the rad cap. It will do this on idle and the needle will go off the scale.

The test for a leaking head gasket is a powder that you put in the header tank. If hydrocarbons are present (oil or petrol) it changes colour. Its not 100% reliable but it will make you look further if you are constantly losing water.

 

Mr Croney, couldn't have put it better myself - David API Engines

 

thanks again 4 your advice pete, what is the powder you mentioned called?

TIA

 

btt

 

Sorry Andy, not been at my desk today.

My man informs me that there's now a new version that you suck coolant up into, made by the same people. Should be easier to see the colour change.

Here you go http://www.hdtools.co.uk/stores/pages/js/p8b.htm

 

A word of caution on using it. If the engine has had a build or if it has been flushed with a solvent based cleaner, it may give a false positive.

 

Thanks very much pete, the car had a rebuild at autosportif 2 years ago, we will give it a go though, once again Thx for your free help!!