a4 1.9 cooling issue

[unders2]

Hi i have a 2002 avant 1.9 tdi reciently it has had a water loss problem but never overheated.

The findings were a small blister in a heater hose at the back of the head so whilst down and waiting for the hose i fitted new thermostat and temp sender also felt the water pump inside the block nothing loose there , also i cleaned out all the inlet and egr of the gunk it was smothered inside with .

All back together  new antifreeze and topped up , sitting on my drive the temp read nothing, after 15 mins or so idling the heaters were hot temp still reading nothing i went for a long run to clear the sh#t out of the head temp came up to 90 after a half mile and everything seemed normal and held at 90 deg even up to a fast pace . covered 40 miles round trip including motorway got back to check the level and the coolant bottle was still cold take off the small pipe and nothing comes out blow down it and it comes up into the bottle ? top hose hot bottom cold could this be rad,  water pump ? car runs as it should but better as ive deleted the egr pipe from exhaust any views on this also would be appreciated thanks guys