How can this be?

[coetzeeh]

Whilst checking the water level in the expansion tank I noticed that the level was up to the top of the tank. The strange bit is that on the previous weekly check it was only half full (up to the weld).

I am no mechanic but it seems that air is getting into the system somehwere?( there is no sign of oil in the water apart from the usual coolant mix). I started the car yesterday with the water reservoir tank cap off and let it idle for 2 or 3 minutes, and there were some bubbles that appeared.

I sometimes also hear what sounds like drinking water through a straw when the glass is almost empty (air and water mix) from the passenger footwell area, or even behind the dash. Can this be the cause of the air in the system?

Please help, and thanks in advance.

Henk

[gingerprince]

Open the brass screw on your swirl pot and have a look at the water level, it should be right to the top. If it's not then it's a sign that you have a leak somewhere. When my radiator was leaking my expansion tank was full but the level in the swirl pot would go down - and that's the important level. It doesn't matter what level the expansion tank is so long as there's "some". And it can't be assumed that if there's water in the expansion tank that there's enough water in the rest of the system.

[geoffvalenti]

gingerprince said:

Open the brass screw on your swirl pot and have a look at the water level, it should be right to the top. If it's not then it's a sign that you have a leak somewhere.

Great advice, but only do this when the engine is stone cold, e.g. first thing in the morning.

You could try bleeding the system at the radiator bleed screw (top LH corner as you face the car)

[Griffter]

I don't think air's getting in - it's just moved from the expansion tank to somewhere in the engine. And the water that it displaced is now in your expansion tank, making the level appear higher. I don't think this is a problem as long as the coolant circulates OK. What you don't want is so much air in one of the cooling channels you get an air lock.
Having said that, no matter how often, or how many times I bleed the air out of the radiator to get the level 'right' it always seems to creep back up (with air ending up in the rad). I've given up doing it now - the car seems to find a 'happy 'level' and stay there.