Having same problem. Just got my 2014 focus titanium x estate 1.6 tdci back today after getting New Timing Belt/Water Pump and Thermostat done. Only had Car a few months. Car doesn't overheat but coolant just disappears. Drove it back from garage coolant was fine when I left but when I got home around expansion tank was wet with coolant. I have just got a new cap for expansion tank so will change it when it cools to see if that makes a difference.

On 4/17/2025 at 1:58 PM, Gaz67 said:

Having same problem. Just got my 2014 focus titanium x estate 1.6 tdci back today after getting New Timing Belt/Water Pump and Thermostat done. Only had Car a few months. Car doesn't overheat but coolant just disappears. Drove it back from garage coolant was fine when I left but when I got home around expansion tank was wet with coolant. I have just got a new cap for expansion tank so will change it when it cools to see if that makes a difference.

When I went to put new expansion cap on coolant was nearly empty. When I loosened cap the coolant refilled to max. Any ideas what the problem is. I'm absolutely stumped with this one. 🤔

5 minutes ago, Gaz67 said:

When I went to put new expansion cap on coolant was nearly empty. When I loosened cap the coolant refilled to max. Any ideas what the problem is. I'm absolutely stumped with this one. 🤔

There's an airlock (bubble) in the cooling system.  Under pressure, coolant squeezes that bubble.  When you release the pressure, the bubble grows back to original size again.

It's possible that it just hasn't been bled properly since the waterpump change.  The alternative is that there is a small crack somewhere, allowing air or exhaust gas into the coolant.

Many thanks Tom.

Think it has to be a crack somewhere as it was doing it before I had the Water Pump changed. So will have to try and work out where crack is.

Thanks again for reply 👍