The water pump and thermostat housing on the EA888 are a known failure point — both are plastic, and both crack and leak with heat cycling.
Symptoms:
- A coolant leak — sweet smell, dropping reservoir, drips around the back/side of the block.
- Temperature swings or overheating as the thermostat sticks.
- The dash coolant warning, or the temp needle wandering.
The fix:
- On the EA888 the water pump and thermostat are one plastic module — replace the whole assembly, not just a seal. Units with a metal impeller/housing are worth the extra.
- Refill with the correct G13/G12++ coolant and bleed the system properly — trapped air causes false overheating.
Do it as a set: if one half has failed the other isn't far behind — replace pump and thermostat together and inspect the hoses.
Bottom line: an EA888 losing coolant with no obvious hose leak is almost always the plastic pump/thermostat module. Catch it before it cooks the aluminium head. See EA888 Timing Chain Tensioner and GTI Service Intervals.