[Ghost Rider]

Just got back to Brum from mid Wales and at Kidderminster steam started coming from the engine no warning from the temp gauge mind. On opening the bonnet I discovered that the expansion tank lid had blown off. I managed to top up the tank as I thought and started off again, this time the gauge went straight up the fans came on and there was a horrible coolant smell. Fortunately I was able to pull down a side road and called the RAC.

The guy at first suspected head gasket (the car is 5 years old and just hit 40K) but after topping up again letting it run awhile then following me for a couple of miles reckoned it was me not tightening up the filler cap enough and it had somehow vibrated loose.

Just checked it again before putting it to bed for the day and the water level is down again below the max line say about half an inch. ANY idea what this is? Is the head gasket on the way out? Is there a leak? There are no obvious signs and the RAC guy did a good check. Am really really worried as I am off to North Wales Sunday and don't want a repeat etc. Please any advice welcome

 

[garythesnail]

If it was just down to the expansion cap, it is possible that, when you topped it up while the engine was cooling down, that there is air trapped in the system and just needs to be topped up and bled - the level has just dropped as things have cooled down fully.

 

[MG ZS STE]

check for mayo underneath your oil filler cap and on the dipstick. if it is HGF then there will be signs of white emulsified oil in these areas. If the level in the expansion tank has only dropped 1/2" it could just be the level settling, depends how much coolant escaped when the cap came loose? You have to keep an eye on your coolant level after the systems been voided as it will drop. Top it up with some fresh OAT and just keep an eye on it.

 

[DeMoNPauL]

I would also change the Cap