Hi and thanks in advance

Not had Fords long (I was a 407SW man for decades) so I'm not sure at all about what's going on with this TDCi, this is mine, I'm not making profit if this gets answered

1. Bought Mondeo from a garage
2. Was losing water BUT: No white smoke, no mayo in oil, no oil in expansion tank but can't see any puddles on road
3. Overheated going to Scotland for a funeral, relayed home, AA thought themostat problems
4. Took it back under warranty, new thermostat, housing and expansion tank
5. Still losing water and out of warranty
6. Checked hoses, checked around expansion tank, had panels off and checked heater matrix - no leaks
7. Had gas test done, no fumes in water BUT high back pressure, mechanic reckons head gasket fine

However, top hose hot, bottom hose hot(ish), heaters hot, nip top hose and release can feel a surge (so pump working) could a blocked radiator core cause it to be stone cold when everything else is hot? Plan on flushing system this weekend but may just swap out radiator, I ask because I can't think it's anything else though some of you may have the answer

Many thanks

PS, what can I do with UCDS, tokens and the cloned cable, I am well acquainted with Lexus/Peugeot Planet having had the upgrade cable and regularly did bits for folk off the forum but I've not had the chance to play with this yet

Cheers
Gaz