water levels low

[pud wayman]

Hi guys,ive gotta vectra cdti 1.9 recently it has been loosing water no leaks i can see then the warning light comes on stating low coolant but when i loosen the expansion cap off then the water levels rise in the tank any ideas guys???

[Critch]

What level is it before starting engine? Do you have to actually top it up?

[pud wayman]

Sorry for the delay in replying its just below the cold water level but when i take off the cap it fills back up also the temp gauge rarely moves thanks in advance

[Critch]

Shouldn't move first think in morning before starting.

Could be an air lock in the system somewhere.

If you top it up to just above the cold marker take it for a drive, get it up to temp and then see if the level drops.

As could be head gasket on way

[pud wayman]

I filled it about an inch above the cold water line ran it till the engine got warm then the level dropped to about the cold line but when i take the expansion cap off it goes back to above the level ?????

[Critch]

Is that you driving around? Or just leaving it idle?

[byebyeitsagsi]

First of all dont take the cap of when the engines hot there is a risk you ended up scalded by steam or boiling coolant.

If the coolant level always returns to the same level when the engine is cold then i suggest the sensor for the coolant level needs replaced.

[pud wayman]

It does it both when the car is idling the level drops,turn the car off the level rises

[pud wayman]

Sorry forgot to say only rises when the cap is taken off

[Ben50n]

The water level will rise when you take the cap off as you are releasing the pressure in the system.