Ford Transit MK8 losing coolant with no visible leak - EGR cooler

A steady drop in coolant level with no puddle under the van is a known sign of a cracked EGR cooler on 2014-2017 Transit MK8 models. The issue was serious enough for these model years to be covered by an official safety recall, because coolant entering the hot exhaust system can create a fire risk. Other symptoms include white, sweet-smelling exhaust smoke and a hissing sound after the engine is switched off. If your van falls within these model years, first ask a Ford dealer whether the recall work has been completed, as the repair may be carried out free of charge. Outside the recall, the EGR cooler is replaced together with its seals, and the EGR valve should be inspected at the same time.