I have a 2003 X350 3.5 V8 47K Miles. Recently had the coolant expansion bottle replaced as I had to put 3 pints in over approx 1K miles and was told this had a hairline crack in the bottom of it. I have covered 60 miles since then but this morning I had to top up by approx. 2 pints.
The specialist I have used for the last 18 months has had a look today, pressure tested, but cannot find any leaks. There was a strong antifreeze smell when I parked up last night, hence why I checked the level this morning. The coolant hoses could be squashed and there are no other signs such as rough running or temperature change when driving or stationary, so I do not suspect head gasket.

Any ideas or help would be appreciated??