Coolant bottle empty 10 minutes after filling but can still drive it for weeks (over 700 miles)

FastLife91

Torque Junkie
Points
57
Location
England
Car
Ford Focus mk2
car - 2006 mk2 ford focus sport 1.8 TDCI.

When I fill coolant tank to max after driving 10 mins or so and I look the bottle is empty but there is enough water in it that I can driver over 700 + miles before I decide to refill despite there being enough water , I know this as when removing cap when hot the water fills the bottle almost then gurgles back down. there is plenty of heat when turning fans on.

Car had a chemical test 14 months ago because it was loosing water very slowly with no leaks, test indicated a possible bad head gasket.
however 14 months on there is no oil/water mixing, no power loss, no smoke, the only symptom is having to top up the water time-time.

If I know for sure head gasket is bad I would replace the head gasket ( friend said he could do it for £430 inc head skim + parts) then I would probably just do it but I suspect other possible big problems with the car so I'm keeping my options open.

here is where I am baffled, When I pour water in the coolant tank if I drive around for 10 minutes or so the water in the coolant bottle is empty but I still am able to drive around for about a month before I decide to refill and whenever I take cap off when engine is hot the water rushes up to the top of the bottle and almost fills the bottle then gurgles down a bit and stops with the water remaining at half way, there is plenty of heat in the car and the heat gets roasting so no problems there. Just wondering why this is ?
 

TCJBOLDIE

Moderator
Staff member
Points
697
Location
Brisbane
Car
2011 Honda FN2
Have you checked to see if there is any air pockets in the cooling system ?

Can you fill the radiator OR can you only add water via the expansion tank ?
 

FastLife91

Torque Junkie
Points
57
Location
England
Car
Ford Focus mk2
Have you checked to see if there is any air pockets in the cooling system ?

Can you fill the radiator OR can you only add water via the expansion tank ?

hi
a few months back after driving long journeys I would see tiny bubbles float from bottom of coolant bottle to the top, but that stopped I think and I have not seen that for a while.

I do not think I can fill the radiator itself but think I can only fill it via the expansion bottle. I do suspect a possible air lock, would that cause these symptoms ? the car does not overheat and I think overheating could be a cause of overheating, but this car doe not, thanks
 

obi_waynne

Administrator
Staff member
Moderator
Points
1,157
Location
Deal, Kent UK
Car
A3 1.4 TFSI 150 COD
It does sound like an air pocket to me. Squeeze the pipes to create flow pulses can help release some of it. In time the air will dissipate as most coolant systems are designed to have the expansion bottle at the highest point where the air will naturally flow to.

Additives in the water can also help dissipate air bubbles, water wetter for example does this job.
 

FastLife91

Torque Junkie
Points
57
Location
England
Car
Ford Focus mk2
It does sound like an air pocket to me. Squeeze the pipes to create flow pulses can help release some of it. In time the air will dissipate as most coolant systems are designed to have the expansion bottle at the highest point where the air will naturally flow to.

Additives in the water can also help dissipate air bubbles, water wetter for example does this job.

thanks.

could air pockets cause radiator hoses to feel quite hard ?

thanks
 

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