Astra losing water but where?

[astraman]

Hi on my 1999 astra when i tap the accelerator i can hear water running noises from behind the dash especially when starting from cold.When the car is actually being drove or just sitting idling there is no noise only when i tap the accelerator.I have had to top up the coollant bottle a few times but cant seem to find any leak from under the car.The car drives okay and the engine temperature is building up okay and the cooling fan is coming on okay.I have no idea what this noise can be and am terrified my head gasket is on the way out and this is just the start.Can anyone give me any idea to whats going on.Thanks for any replies.

[david1702198]

all you can hear is coolant circulating in the heater matrix behind the dash. when you start the car up the water pump forces the coollant around the engine and colling systm.

[Full Tilt]

Hi Dave, I see where your coming from but if the engine is cold and the stat is shut how can the coolant circulate until running temp. is reached and the stat opens (what do you think). FT

[colin6789]

I think a lot of cars the heater martix is in the thermostat by pass so water is flowing all the time the engine is running. The noise could be air in the cooling system like a domestic heating system. some cars can be a devil to bleed to get the air out, but it may slowly come out each time the engine is run so it seems to be loosing water. It could be the hose or joint on the inlet side of the water pump is leaking and this is pulling air into the system, difficult to find, does the system loose pressure quickly when the engine is stopped from hot., can you hear a small leak from the enines just after it as stopped.

[cazzz1975]

are you topping up the coolant to the level or over?

[astraman]

The car seems to be building up pressure okay and the heaters are woking okay it just keeps losing water and there are no visible signs of where its going.The carpets are not wet either neither is there oil in the water bottle and the oil and its level looks okay.I have been filling the coolant bottle over its normal level but it just comes back down.If my head gasket has gone would the temperature gauge not go through the roof as ive had that happen on another car?On this car the temp is building up okay and when ive left it its went back down when the cooling fan has kicked in so does this rule out gasket failure?

[colin6789]

I think it is air in the system but how you get it out I do not know.

[cazzz1975]

anything over the max line will get blown out automatically, its an expansion tank, water needs to expand so you shouldnt fill it to the top only to the max, if you overfill it will blow out through the cap, bringing it back to max level.