Ok guys.
Doscover 2 1999 TD5 144,000 miles.
I have just changed my cylinder head gasket. All seems good. No pressue in coolant etc. No blowback from oil dipstick, or contamination of oil.
Found Intrercooler was blown, so also renwed that,.. and
MAf sensor,
Turbo Hoses,
Coolant temp...