In the EA211 the water pump and the thermostat are one plastic module, and the pump is driven not by the timing belt but by a separate toothed belt behind the exhaust camshaft. There are usually two problems with it: the plastic housing warps or cracks (slow coolant loss, a sweet smell, rising temperature), or the drive belt ages (a chirping noise, then an engine left with no cooling). The housing is particularly sensitive if oil reaches it: for example from a leaking crankcase ventilation. The module has to be replaced whole: dismantling it warps it in itself.
What to check
- Check the level in the expansion tank, and ask whether it needs topping up
- After a cold start smell the engine bay: a sweet smell means coolant
- Look for dried, whitish pink deposits on the exhaust side of the cylinder head
