Why is my Peugeot 208 using so much coolant?

My Peugeot 208 1.4 petrol runs at around 96-98 degrees and the engine is using a lot of coolant every week. I've called out the AA, but they say this operating temperature is normal. The temp doesn't go any higher and otherwise drives fine, but I'm concerned after seeing a wet patch under the car when the engine is switched off. The wet patch is always underneath the coolant bottle/pipes and makes me think that it’s not the radiator or water pump. Peugeot have washed their hands of it after finding no fault. Any ideas?

Asked on 7 December 2016 by Ben Spriggs

Answered by Honest John
Will be caused by an airlock in the cooling system created when you started using the heater again after the summer. That pressurises the system and blows coolant out of the expansion tank pressure cap. Simply needs purging. Might work to take the expansion tank cap off and from stone cold run the engine up to running temperature when thermostat opens and fans start. The airlock should then gurgle through and you can replace the cap sharpish before the coolant blows out.
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