[Hutch43221]

Coolant bottle keeps emptying and when you put the heating on in the car the temp gauge goes down to cold what could.it be

 

[oberlisc]

Welcome to the Forum

Are there any staining from leaks, if you look at the bulkhead/firewall (as the Americans call it ) there should be 2 pipes that go through this to the heater matrix is there any staining on the bulk, also check your carpets in the front foot well for dampness.

Other than that take your dipstick out and check for a mayo like substance, also check on the oil filler cap, if it is present this could be why your loosing water the head gasket has failed.

 

[Hilary16v]

get a pressure tester, check the cap and after filling up with coolant, not just water, pressure test and under pressure, look for leaks... always check with heater fully open... then if you see nothing outside, look at your carpets as the inner heat exchanger could be leaking.

With the description you've given, it could be anything, does the fan come on ? when did you notice this and what changed?

 

[DilligaX]

Coolant bottle keeps emptying

What engine you have? Any leaks down the engine or front bumper, any strange smell when you open the bonnet with hot engine?

when you put the heating on in the car the temp gauge goes down to cold what could.it be

I would put my bet on thermostat.

 

[Hilary16v]

I would agree with @Hutch43221 easy enough to do. Buy a new housing, because they're plastic they break really easy but to test, take it out and then get a thermometer, put the thermostat in the kettle while its on the boil and take note of what temperature it opens , if indeed it does.


if it doesn't then replace. if it does, take notice of the temperature. sometimes it gets airlocks. Drill a 3mm hole in the outer round disk of the thermostat, the inner one opens and closes.

the bleed hole helps the air bleed out of the system.

assuming it opens at 78-90 deg c its ok but if it opens above 100 you have a problem. get a new one.