Pressurised water system

[Jezcar]

Hi all

Recently bought the wife a 52 plate 1.3 KA, as a stop gap until new car can be bought, when she first used it we found the heater control valve had failed (continuous hot air regardless of control position) I have now replaced this and she now has control over air temp of heater.

However since replacing control valve the engine management light has come on (goes off sometimes but comes back on) also we now have the water system pressurising and today she's had the dash temp light come on. Never had any of these issues prior to replacing the control valve.

Have I managed to get an air lock at thermotat that hasn't cleared, if so how do I remove it? Could the thermostat have failed at exactly the time I replaced control Valve? I'm waiting for her to return home so I can have a look at it.

To me a pressurised system is an indicator of head gasket failure, but have read water fill cap and thermostat can cause this too.

Any help would be great but really hope its not the HG as don't want the hassle of replacement as that means she'll have to drive me to work so she can have my car for her work, which isn't an issue it's the 150miles each day that is lol.

Edit. Wife now home checked out and found radiator is cold so assume an air lock but how do I get rid of it?

Thanks in advance.

Jez

[Luke4efc]

Best going on YouTube on how to bleed the radiator, but it does sound like you've introduced air into the system.

Basically take the fill cap off and put heater to full. Some people actually take the thermostat out to speed the process up, but you're best just waiting for the car to get to temp so it will open by itself. The air should bleed itself out provided you've opened up the highest point of the system and you've enough coolant in the reservoir. If not then a good trick is to rev the car up and bit and it will "burp" out.

[steveras1957]

Hi fella

here a method i used often to clear air locks in old mitsubushi pajeros

 Park the car facing uphill as steep as possible (you want the radiator at the highest point) take of the radiator cap if possible or the expansion tank cap if not.

run the engine up to temp with the cap off and the heater controls set to maximum let it get good and hot (at least twenty minutes) so water completly curculates the system ie-heater matrix&thermostat etc.

the parking uphill allows any trapped air to rise through the system and escape!

if the system boils over ie- water pours out the cap- turn off and let cool for a few minutes then start again

its a good idea to watch the system (at whichever cap you have off) whilst doing this (but not to close now-safety first etc) if its working you should see little bubbles or "spits" of water as the trapped air is vented, we used to call this system "burping" the radiator for obvious reasons.

once no more air is being expelled turn everything of and go have a cup of tea(to allow things to cool a bit,after about half an hour go back and top up the coolent to the correct levels id use a 50/50 mix of anti freeze and distilled water re-fill slow so as not to introduce more air, once refilled restart car and check problems have cleared ,warning lights go out, heater works ,and car drives ok.

works 9 times out of ten if not first time then allow to cool overnight and try again!

if that dont clear it then you you might need to remove the thermostat and light pressure flush the system!

good luck with it