So…
Audi put on ebay, 1 day later and some chap came and picked it up and gave me £900.
Mate also waived the fee for the 806 (actually a Citroen Synergie), instead I have to help him lay a lawn.. wish I just paid him tbh.
Anyway, had a go at fixing the Synergie today – replaced the thermostat.
Hasn’t seem to have made a difference, still loses water from the expansion tank cap.
Symptoms/observations:
No oil in coolant, radiator hose hot incoming and slightly cooler on outlet as expected. No apparent scum on filler cap – although it’s more of a flexible filler tube.
Drives very well, engine sounds nice and turbo seems to pull as expected.
Any ideas? Water pump? Surely an issue with the head gasket/head would show some other symptoms?